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1

Mean free-path length theory of predator–prey interactions: Application to juvenile salmon migration  

Microsoft Academic Search

Ecological theory traditionally describes predator–prey interactions in terms of a law of mass action in which the prey mortality rate depends on the density of predators and prey. This simplifying assumption makes population-based models more tractable but ignores potentially important behaviors that characterize predator–prey dynamics. Here, we expand traditional predator–prey models by incorporating directed and random movements of both predators

James J. Anderson; Eliezer Gurarie; Richard W. Zabel

2005-01-01

2

Parameter Estimation Techniques for Interaction and Redistribution Models of Species Interactions: A Predator-Prey Example.  

National Technical Information Service (NTIS)

The use of parameter estimation techniques for partial differential equations is illustrated using a predator-prey model. These techniques will be general useful for any interaction and redistribution model in ecology, and can even be used to treat spatia...

H. T. Banks P. M. Kareiva K. A. Murphy

1986-01-01

3

Chytridiomycosis impacts predator-prey interactions in larval amphibian communities.  

PubMed

Despite ecologists increasingly recognizing pathogens as playing significant roles in community dynamics, few experimental studies have quantified patterns of disease impacts on natural systems. Amphibians are experiencing population declines, and a fungal pathogen ( Batrachochytrium dendrobatidis; Chytridiomycota) is a suspected causal agent in many declines. We studied the effects of a pathogenic fungus on community interactions between the gray treefrog, Hyla chrysoscelis, and eastern newts, Notophthalmus viridescens. Recent studies have characterized chytridiomycosis as an emerging infectious disease, whose suspected rapid range expansion and widespread occurrence pose a significant risk for amphibian populations worldwide. We reared larvae in outdoor polyethylene experimental tanks and tested the effects of initial larval density, predator presence, and fungal exposure on Hyla recruitment and predator-prey interactions between Hyla and Notophthalmus. Newts reduced treefrog survival, and high intraspecific density decreased metamorphic body mass independent of B. dendrobatidis. The presence of fungi reduced treefrog body mass at metamorphosis by 34%, but had no significant main effect on survival or larval period length. B. dendrobatidis differentially affected larval development in the presence of predators; Hyla developed slower when reared with the pathogen, but only when newts were present. This significant predator-by-pathogen interaction suggests that the impact of chytridiomycosis on larval amphibians may be exacerbated in complex communities. Our data suggest that B. dendrobatidis effects on host life history may be complex and indirect. Direct measurements of the community-level effects of pathogens offer an important opportunity to understand a significant threat to global biodiversity-declining amphibian populations. PMID:15235903

Parris, Matthew J; Beaudoin, Joseph G

2004-07-03

4

Chemical ecology of predator?prey interactions in ctenophores  

Microsoft Academic Search

Two species of ctenophores coexist in the north?east Atlantic, one (Bolinopsis infundibulum) forages on crustaceans, while the other (Beroë cucumis) feeds exclusively on the former. Some introductory aspects on the chemical ecology of this predator?prey relationship are reported here. In laboratory experiments, Bolinopsis demonstrated an escape response to mechanical stimuli directed towards the frontal lobes, as well as to direct

Tone Falkenhaug; Ole B. Stabell

1996-01-01

5

Complex predator-prey interactions and predator intimidation among crayfish, piscivorous fish, and small benthic fish  

Microsoft Academic Search

Predator-prey interactions were studied among a small prey fish (the johnny darter Etheostoma nigrum) and two predators (crayfish Orconectes rusticus and smallmouth bass Micropterus dolomieui) with complementary foraging behaviors. When only smallmouth bass were present, darters reduced activity to 6% of control rates and spent most of the time hiding under tile shelters. When only crayfish were present, darter activity

Frank J. Rahel; Roy A. Stein

1988-01-01

6

Predator-Prey Models  

NSDL National Science Digital Library

Using Maple, Mathmatica, or MatLab, learner should be able to develop the Lotka-Volterra model for predator-prey interactions and a two-populaton version of Eulers Method for solving a system of differential equations.

Smith, David

2001-01-22

7

Predator-Prey Models  

NSDL National Science Digital Library

Using Maple, Mathmatica, or MatLab, learner should be able to develop and explore the Lotka-Volterra model for predator-prey interactions as a prototypical first-order system of differential equations.

Smith, David

2001-01-30

8

Elevated CO2 affects predator-prey interactions through altered performance.  

PubMed

Recent research has shown that exposure to elevated carbon dioxide (CO2) affects how fishes perceive their environment, affecting behavioral and cognitive processes leading to increased prey mortality. However, it is unclear if increased mortality results from changes in the dynamics of predator-prey interactions or due to prey increasing activity levels. Here we demonstrate that ocean pCO2 projected to occur by 2100 significantly effects the interactions of a predator-prey pair of common reef fish: the planktivorous damselfish Pomacentrus amboinensis and the piscivorous dottyback Pseudochromis fuscus. Prey exposed to elevated CO2 (880 µatm) or a present-day control (440 µatm) interacted with similarly exposed predators in a cross-factored design. Predators had the lowest capture success when exposed to elevated CO2 and interacting with prey exposed to present-day CO2. Prey exposed to elevated CO2 had reduced escape distances and longer reaction distances compared to prey exposed to present-day CO2 conditions, but this was dependent on whether the prey was paired with a CO2 exposed predator or not. This suggests that the dynamics of predator-prey interactions under future CO2 environments will depend on the extent to which the interacting species are affected and can adapt to the adverse effects of elevated CO2. PMID:23484032

Allan, Bridie J M; Domenici, Paolo; McCormick, Mark I; Watson, Sue-Ann; Munday, Philip L

2013-03-06

9

Signalling displays during predator–prey interactions in a Puerto Rican anole, Anolis cristatellus  

Microsoft Academic Search

We examined conspicuous signalling displays in the context of predator–prey interactions. To determine in which context Puerto Rican crested anoles,Anolis cristatellusperform conspicuous signals, we exposed wild lizards to a model of a natural snake predator. The lizards gave six behavioural responses to the model: immobility, predator inspection, flight, lateral face-off, dewlapping and push-ups. They displayed significantly more push-ups and push-up

MANUEL LEAL; JAVIER A. RODRIuGUEZ-ROBLES

1997-01-01

10

Predator-prey interactions: is 'ecological stoichiometry' sufficient when good food goes bad?  

Microsoft Academic Search

The dietary value of a prey type varies with its nutritional status and hence with its C:N:P content. However, while stoichiometric differences between a heterotroph and its food must affect growth efficiency (GE), and thence trophic dynamics, other factors related to food quality may act as powerful modulators of predator-prey interactions. Thus, minor changes in prey stoichiometry can be associated

Aditee Mitra; Kevin J Flynn

2005-01-01

11

Community-wide distribution of predator-prey interaction strength in kelp forests  

PubMed Central

The strength of interactions between predators and their prey (interaction strength) varies enormously among species within ecological communities. Understanding the community-wide distribution of interaction strengths is vital, given that communities dominated by weak interactions may be more stable and resistant to invasion. In the oceans, previous studies have reported log-normal distributions of per capita interaction strength. We estimated the distribution of predator–prey interaction strengths within a subtidal speciose herbivore community (45 species). Laboratory experiments were used to determine maximum per capita interaction strengths for eight species of herbivores (including amphipods, isopods, gastropods, and sea urchins) that graze on giant kelp (Macrocystis pyrifera) microscopic stages. We found that maximum per capita interaction strength saturated as a function of individual herbivore biomass, likely caused by predator/prey size thresholds. Incorporating this nonlinearity, we predicted maximum per capita interaction strength for the remaining herbivore species. The resulting distribution of per capita interaction strengths was bimodal, in striking contrast to previous reports from other communities. Although small herbivores often had per capita interaction strengths similar to larger herbivores, their tendency to have greater densities in the field increased their potential impact as grazers. These results indicate that previous conclusions about the distributions of interaction strength in natural communities are not general, and that intermediate-sized predators can under realistic circumstances represent the most effective consumers in natural communities.

Sala, Enric; Graham, Michael H.

2002-01-01

12

Testing interaction in some predator–prey populations  

Microsoft Academic Search

This paper deals with a testing problem for each of the interaction parameters of the Lotka–Volterra ordinary differential\\u000a equations system~(ODE). In short, when the rates of birth and death are fixed, we would like to test if each interaction parameter\\u000a is higher or lower than a fixed reference rate. We choose a statistical model where the actual population sizes are

Sévérien Nkurunziza

2009-01-01

13

Shifts in the Trophic Ecology of Brook Trout Resulting from Interactions with Yellow Perch: An Intraguild Predator-Prey Interaction  

Microsoft Academic Search

In size-structured populations, predator-prey interactions may be preceded by a phase of resource competition earlier in ontogeny, with potential consequences for population dynamics and resource management. We hypothesized that brook trout Salvelinus fontinalis and yellow perch Perca flavescens would compete for shared resources and interact as predator and prey. We used stable isotopes and stomach content analysis to compare the

David R. Browne; Joseph B. Rasmussen

2009-01-01

14

Thermal acclimation of interactions: differential responses to temperature change alter predator-prey relationship  

PubMed Central

Different species respond differently to environmental change so that species interactions cannot be predicted from single-species performance curves. We tested the hypothesis that interspecific difference in the capacity for thermal acclimation modulates predator–prey interactions. Acclimation of locomotor performance in a predator (Australian bass, Macquaria novemaculeata) was qualitatively different to that of its prey (eastern mosquitofish, Gambusia holbrooki). Warm (25°C) acclimated bass made more attacks than cold (15°C) acclimated fish regardless of acute test temperatures (10–30°C), and greater frequency of attacks was associated with increased prey capture success. However, the number of attacks declined at the highest test temperature (30°C). Interestingly, escape speeds of mosquitofish during predation trials were greater than burst speeds measured in a swimming arena, whereas attack speeds of bass were lower than burst speeds. As a result, escape speeds of mosquitofish were greater at warm temperatures (25°C and 30°C) than attack speeds of bass. The decline in the number of attacks and the increase in escape speed of prey means that predation pressure decreases at high temperatures. We show that differential thermal responses affect species interactions even at temperatures that are within thermal tolerance ranges. This thermal sensitivity of predator–prey interactions can be a mechanism by which global warming affects ecological communities.

Grigaltchik, Veronica S.; Ward, Ashley J. W.; Seebacher, Frank

2012-01-01

15

Effect of Culverts on Predator-Prey Interactions in a Tropical Stream.  

NASA Astrophysics Data System (ADS)

As part of a biocomplexity project in Puerto Rico, we use river and road networks as a platform to understand the interactions between stream biota, the physical environment, and human activity. Specifically, we ask if humans affect aquatic organisms through road building and recreational activities. Culverts have been documented to impede or slow migration of aquatic biota. This is especially important in these streams because all of the freshwater, stream species have diadramous life cycles. If culverts do act as bottlenecks to shrimp migrations, we expect altered predator-prey interactions downstream through density-dependent predation dynamics. In order to determine how roads may affect predation rates on upstream migrating shrimp, we parameterized functional response curves for mountain mullet (Agonostomus monticola) consuming shrimp (Xiphocaris sp.) using artificial mesocosm experiments. We then used data obtained from underwater videography to determine how culverts decrease the rate and number of shrimp moving upstream. These data were combined in a predator-prey model to quantify the effects of culverts on localized shrimp densities and fish predation.

Hein, C. L.; Kikkert, D. A.; Crowl, T. A.

2005-05-01

16

Predator-prey interactions shape thermal patch use in a newt larvae-dragonfly nymph model.  

PubMed

Thermal quality and predation risk are considered important factors influencing habitat patch use in ectothermic prey. However, how the predator's food requirement and the prey's necessity to avoid predation interact with their respective thermoregulatory strategies remains poorly understood. The recently developed 'thermal game model' predicts that in the face of imminent predation, prey should divide their time equally among a range of thermal patches. In contrast, predators should concentrate their hunting activities towards warmer patches. In this study, we test these predictions in a laboratory setup and an artificial environment that mimics more natural conditions. In both cases, we scored thermal patch use of newt larvae (prey) and free-ranging dragonfly nymphs (predators). Similar effects were seen in both settings. The newt larvae spent less time in the warm patch if dragonfly nymphs were present. The patch use of the dragonfly nymphs did not change as a function of prey availability, even when the nymphs were starved prior to the experiment. Our behavioral observations partially corroborate predictions of the thermal game model. In line with asymmetric fitness pay-offs in predator-prey interactions (the 'life-dinner' principle), the prey's thermal strategy is more sensitive to the presence of predators than vice versa. PMID:23755175

Gvoždík, Lumír; ?ernická, Eva; Van Damme, Raoul

2013-06-03

17

Sublethal effects and predator-prey interactions: implications for ecological risk assessment.  

PubMed

Ecological risk assessments tend to focus on contaminant effects on single species in isolation. However, additional effects from interactions between species (e.g., predator-prey interactions) may also occur in natural systems. The present study investigated the consequences of sublethal contaminant effects in prey on predator-prey interactions, particularly the interaction between prey behavioral changes and predation by predators with different hunting strategies. Ambush (Ischnura elegans Vander Linden [Insecta, Odonata]) and active (Notonecta glauca Linnaeus [Insecta, Heteroptera]) predator species were used in conjunction with three prey species (Asellus aquaticus Linnaeus [Crustacea, Isopoda], Cloion dipterum Linnaeus [Insecta, Ephemeroptera], and Chironomus riparius Meigen [Insecta, Diptera]). Immobilized prey demonstrated the importance of prey behavior for determining predation rates for both single- and multiple-prey species. Chironomus riparius was less responsive following exposure to cadmium, becoming more vulnerableto attack by the active but not the ambush predator. Some evidence was also observed for reduced general activity in C. dipterum following cadmium exposure. Sublethal exposure of prey did not affect the prey choice of active predators, possibly because of prey behavioral changes being insufficient to influence their relative availabilities. However, cadmium exposure of prey did alter their susceptibility to ambush predators. There was a reduced proportion of C. dipterum and an increased proportion of A. aquaticus in the diet of ambush predators, possibly because of reduced activity in C. dipterum affecting their relative encounter rates with predators. Sublethal exposures can therefore result in reduced prey survival that would not be predicted by single-species toxicity tests. PMID:19572771

Brooks, Amy C; Gaskell, Paul N; Maltby, Lorraine L

2009-11-01

18

On Role of Implicit Interaction and Explicit Communications in Emergence of Social Behavior in Continuous Predators-Prey Pursuit Problem  

Microsoft Academic Search

We present the result of our work on use of genetic programming for evolving social behavior of agents situated in inherently cooperative environ- ment. We use predators-prey pursuit problem to verify our hypothesis that rela- tively complex social behavior may emerge from simple, implicit, locally de- fined, and therefore - robust and highly-scalable interactions between the predator agents. We propose

Ivan Tanev; Katsunori Shimohara

2003-01-01

19

Do Predators Always Win? Starfish versus Limpets: A Hands-On Activity Examining Predator-Prey Interactions  

ERIC Educational Resources Information Center

|In this article we propose a hands-on experimental activity about predator-prey interactions that can be performed both in a research laboratory and in the classroom. The activity, which engages students in a real scientific experiment, can be explored not only to improve students' understanding about the diversity of anti-predator behaviors but…

Faria, Claudia; Boaventura, Diana; Galvao, Cecilia; Chagas, Isabel

2011-01-01

20

Predator-prey interactions between blue crabs and ribbed mussels living in clumps  

NASA Astrophysics Data System (ADS)

Predator-prey interactions between blue crabs ( Callinectes sapidus) and ribbed mussels ( Geukensia demissa) were studied by manipulating different components of mussel clump structure in the laboratory to test their effects on the mussels' susceptibility to crab predation. Mussels with stronger attachment strength or those buried deeper in the sediment suffered lower mortality. Blue crabs showed no significant size selectivity when two size classes of mussles (30-40 and 50-60 mm in shell heights) were offered. When juvenile mussels were attached to adult conspecifics and completely buried in the centres of clumps as in the field, blue crabs did not actively search for them. The crabs, however, did consume juveniles as by-products when they preyed upon the adult mussels to which the juveniles were attached.

Lin, Junda

1991-01-01

21

Effects of Learning to Interact on the Evolution of Social Behavior of Agents in Continuous Predators-Prey Pursuit Problem  

Microsoft Academic Search

\\u000a We present the results of our work on the effect of learning to interact on the evolution of social behavior of agents situated\\u000a in inherently cooperative environment. Using continuous predators-prey pursuit problem we verified our hypothesis that relatively\\u000a complex social behavior may emerge from simple, implicit, locally defined, and therefore – robust and highly-scalable interactions\\u000a between the predator agents. We

Ivan Tanev; Katsunori Shimohara

2003-01-01

22

Effects of quenched randomness on predator-prey interactions in a stochastic Lotka-Volterra lattice model  

NASA Astrophysics Data System (ADS)

We study the influence of spatially varying reaction rates (i.e., quenched randomness) on a stochastic two-species Lotka-Volterra lattice model for predator-prey interactions using Monte Carlo simulations. The effects on the asymptotic population densities, transient oscillations, spatial distributions, and on traveling wave and invasion front speed velocities are investigated. We find that spatial variability in the predation rate yields an increase in the asymptotic population densities of both predators and prey.

Tauber, Uwe C.; Dobramysl, Ulrich

2008-03-01

23

Clay Caterpillar Whodunit: A Customizable Method for Studying Predator-Prey Interactions in the Field  

ERIC Educational Resources Information Center

|Predator-prey dynamics are an important concept in ecology, often serving as an introduction to the field of community ecology. However, these dynamics are difficult for students to observe directly. We describe a methodology that employs model caterpillars made of clay to estimate rates of predator attack on a prey species. This approach can be…

Curtis, Rachel; Klemens, Jeffrey A.; Agosta, Salvatore J.; Bartlow, Andrew W.; Wood, Steve; Carlson, Jason A.; Stratford, Jeffrey A.; Steele, Michael A.

2013-01-01

24

Revisiting the classics: considering nonconsumptive effects in textbook examples of predator-prey interactions.  

PubMed

Predator effects on prey dynamics are conventionally studied by measuring changes in prey abundance attributed to consumption by predators. We revisit four classic examples of predator-prey systems often cited in textbooks and incorporate subsequent studies of nonconsumptive effects of predators (NCE), defined as changes in prey traits (e.g., behavior, growth, development) measured on an ecological time scale. Our review revealed that NCE were integral to explaining lynx-hare population dynamics in boreal forests, cascading effects of top predators in Wisconsin lakes, and cascading effects of killer whales and sea otters on kelp forests in nearshore marine habitats. The relative roles of consumption and NCE of wolves on moose and consequent indirect effects on plant communities of Isle Royale depended on climate oscillations. Nonconsumptive effects have not been explicitly tested to explain the link between planktonic alewives and the size structure of the zooplankton, nor have they been invoked to attribute keystone predator status in intertidal communities or elsewhere. We argue that both consumption and intimidation contribute to the total effects of keystone predators, and that characteristics of keystone consumers may differ from those of predators having predominantly NCE. Nonconsumptive effects are often considered as an afterthought to explain observations inconsistent with consumption-based theory. Consequently, NCE with the same sign as consumptive effects may be overlooked, even though they can affect the magnitude, rate, or scale of a prey response to predation and can have important management or conservation implications. Nonconsumptive effects may underlie other classic paradigms in ecology, such as delayed density dependence and predator-mediated prey coexistence. Revisiting classic studies enriches our understanding of predator-prey dynamics and provides compelling rationale for ramping up efforts to consider how NCE affect traditional predator-prey models based on consumption, and to compare the relative magnitude of consumptive and NCE of predators. PMID:18831163

Peckarsky, Barbara L; Abrams, Peter A; Bolnick, Daniel I; Dill, Lawrence M; Grabowski, Jonathan H; Luttbeg, Barney; Orrock, John L; Peacor, Scott D; Preisser, Evan L; Schmitz, Oswald J; Trussell, Geoffrey C

2008-09-01

25

A link between water availability and nesting success mediated by predator-prey interactions in the Arctic.  

PubMed

Although water availability is primarily seen as a factor affecting food availability (a bottom-up process), we examined its effect on predator-prey interactions through an influence on prey behavior (a top-down process). We documented a link between water availability, predation risk, and reproductive success in a goose species (Chen caerulescens atlantica) inhabiting an Arctic environment where water is not considered a limited commodity. To reach water sources during incubation recesses, geese nesting in mesic tundra (low water availability) must move almost four times as far from their nest than those nesting in wetlands, which reduced their ability to defend their nest against predators and led to a higher predation rate. Nesting success was improved in high rainfall years due to increased water availability, and more so for geese nesting in the low water availability habitat. Likewise, nesting success was improved in years where the potential for evaporative water loss (measured by the atmospheric water vapor pressure) was low, presumably because females had to leave their nest less often to drink. Females from water-supplemented nests traveled a shorter distance to drink, and their nesting success was enhanced by 20% compared to the control. This shows that water availability and rainfall can have a strong effect on predator-prey dynamics and that changes in precipitation brought by climate change could have an impact on some Arctic species through a top-down effect. PMID:19323230

Lecomte, Nicolas; Gauthier, Gilles; Giroux, Jean-François

2009-02-01

26

Effects of aroclor 1254 and No. 2 fuel oil, singly and in combination, on predator-prey interactions in coho salmon ( Oncorhynchus kisutch )  

Microsoft Academic Search

The effects of No. 2 fuel oil on predator-prey interactions of coho salmon were examined. Since aquatic organisms under natural conditions are simultaneously exposed to more than one toxicant, the effects of fuel oil plus polychlorinated biphenyls (PCBs) were also evaluated. Experimental fish were either injected with a single intraperitoneal dose of 150 g\\/kg Aroclor 1254, exposed to fuel oil

Leroy C. Folmar; Harold O. Hodgins

1982-01-01

27

Exponential Runge-Kutta integrators for modelling Predator-Prey interactions  

NASA Astrophysics Data System (ADS)

Spatially explicit models consisting of reaction-diffusion partial differential equations are considered in order to model prey-predator interactions, since it is known that the role of spatial processes reveals of great interest in the study of the effects of habitat fragmentation on biodiversity. As almost all of the realistic models in biology, these models are nonlinear and their solution is not known in closed form. Our aim is approximating the solution itself by means of exponential Runge-Kutta integrators. Moreover, we apply the shift-and-invert Krylov approach in order to evaluate the entire functions needed for implementing the exponential method. This numerical procedure reveals to be very eff cient in avoiding numerical instability during the simulation, since it allows us to adopt high order in the accuracy. This work has received funding from the European Union's Seventh Framework Programme FP7/2007-2013, SPA.2010.1.1-04: ``Stimulating the development of GMES services in specif c are'', under grant agreement 263435, project title: Biodiversity Multi-Source Monitoring System:from Space To Species (BIOSOS) coordinated by CNR-ISSIA, Bari-Italy (http://www.biosos.eu).

Diele, F.; Marangi, C.; Ragni, S.

2012-09-01

28

Pulsed-resource dynamics constrain the evolution of predator-prey interactions.  

PubMed

Although temporal variability in the physical environment plays a major role in population fluctuations, little is known about how it drives the ecological and evolutionary dynamics of species interactions. We studied experimentally how extrinsic resource pulses affect evolutionary and ecological dynamics between the prey bacterium Serratia marcescens and the predatory protozoan Tetrahymena thermophila. Predation increased the frequency of defensive, nonpigmented prey types, which bore competitive costs in terms of reduced maximum growth rate, most in a constant-resource environment. Furthermore, the predator densities of the pulsed-resource environment regularly fluctuated above and below the mean predator densities of the constant environment. These results suggest that selection favored fast-growing competitor prey types over defensive but slower-growing prey types more often in the pulsed-resource environment (abundance of resources and low predation risk). As a result, the selection for prey defense fluctuated more in the pulsed-resource environment, leading to a weaker mean response in prey defense. At the ecological level, the evolution of prey defense weakened the relative strength of top-down regulation on prey community. This was more evident in the constant-resource environment, whereas the slow emergence of defensive prey types gradually decreased the amplitude of predator peaks in the pulsed-resource environment. Our study suggests that rapid evolution plays a smaller role in the ecological dynamics of communities dominated by resource pulses. PMID:21460542

Friman, Ville-Petri; Laakso, Jouni

2011-03-01

29

Cannibalism in an age-structured predator-prey system  

Microsoft Academic Search

Recently, Kohlmeier and Ebenhöh showed that cannibalism can stabilize population cycles in a Lotka-Volterra type predator-prey model. Population cycles in their model are due to the interaction between logistic population growth of the prey and a hyperbolic functional response. In this paper, we consider a predator-prey system where cyclic population fluctuations are due to the age structure in the predator

Wilfried Gabriel

1997-01-01

30

Cannibalism in an age-structured predator-prey system  

Microsoft Academic Search

Recently, Kohlmeier and Ebenhh showed that cannibalism can stabilize population cycles in a Lotka-Volterra type predator-prey\\u000a model. Population cycles in their model are due to the interaction between logistic population growth of the prey and a hyperbolic\\u000a functional response. In this paper, we consider a predator-prey system where cyclic population fluctuations are due to the\\u000a age structure in the predator

Frank Van den Bosch; Wilfried Gabriel

1997-01-01

31

Predator-prey molecular ecosystems.  

PubMed

Biological organisms use intricate networks of chemical reactions to control molecular processes and spatiotemporal organization. In turn, these living systems are embedded in self-organized structures of larger scales, for example, ecosystems. Synthetic in vitro efforts have reproduced the architectures and behaviors of simple cellular circuits. However, because all these systems share the same dynamic foundations, a generalized molecular programming strategy should also support complex collective behaviors, as seen, for example, in animal populations. We report here the bottom-up assembly of chemical systems that reproduce in vitro the specific dynamics of ecological communities. We experimentally observed unprecedented molecular behaviors, including predator-prey oscillations, competition-induced chaos, and symbiotic synchronization. These synthetic systems are tailored through a novel, compact, and versatile design strategy, leveraging the programmability of DNA interactions under the precise control of enzymatic catalysis. Such self-organizing assemblies will foster a better appreciation of the molecular origins of biological complexity and may also serve to orchestrate complex collective operations of molecular agents in technological applications. PMID:23176248

Fujii, Teruo; Rondelez, Yannick

2012-12-17

32

Global qualitative analysis of a ratio-dependent predator–prey system  

Microsoft Academic Search

.  ?Ratio-dependent predator–prey models are favored by many animal ecologists recently as more suitable ones for predator–prey\\u000a interactions where predation involves searching process. However, such models are not well studied in the sense that most\\u000a results are local stability related. In this paper, we consider the global behaviors of solutions of a ratio-dependent predator–prey\\u000a systems. Specifically, we shall show that ratio

Yang Kuang; Edoardo Beretta

1998-01-01

33

Chemotactic predator-prey dynamics  

NASA Astrophysics Data System (ADS)

A discrete chemotactic predator-prey model is proposed in which the prey secrets a diffusing chemical which is sensed by the predator and vice versa. Two dynamical states corresponding to catching and escaping are identified and it is shown that steady hunting is unstable. For the escape process, the predator-prey distance is diffusive for short times but exhibits a transient subdiffusive behavior which scales as a power law t1/3 with time t and ultimately crosses over to diffusion again. This allows us to classify the motility and dynamics of various predatory microbes and phagocytes. In particular, there is a distinct region in the parameter space where they prove to be infallible predators.

Sengupta, Ankush; Kruppa, Tobias; Löwen, Hartmut

2011-03-01

34

Spatial price equilibrium and food webs: The economics of predator-prey networks  

Microsoft Academic Search

In this paper, we prove that the equilibrium of predator-prey networks is, in fact, a spatial price equilibrium. This result demonstrates the underlying economics of predator- prey relationships and interactions and provides a foundation for the formulation and analysis of complex food webs, which are nature's supply chains, through the formalism of network equilibrium. Moreover, it rigorously links the equilibrium

Anna Nagurney; Ladimer S. Nagurney

2011-01-01

35

Putting prey and predator into the CO2 equation--qualitative and quantitative effects of ocean acidification on predator-prey interactions.  

PubMed

Little is known about the impact of ocean acidification on predator-prey dynamics. Herein, we examined the effect of carbon dioxide (CO(2)) on both prey and predator by letting one predatory reef fish interact for 24 h with eight small or large juvenile damselfishes from four congeneric species. Both prey and predator were exposed to control or elevated levels of CO(2). Mortality rate and predator selectivity were compared across CO(2) treatments, prey size and species. Small juveniles of all species sustained greater mortality at high CO(2) levels, while large recruits were not affected. For large prey, the pattern of prey selectivity by predators was reversed under elevated CO(2). Our results demonstrate both quantitative and qualitative consumptive effects of CO(2) on small and larger damselfish recruits respectively, resulting from CO(2)-induced behavioural changes likely mediated by impaired neurological function. This study highlights the complexity of predicting the effects of climate change on coral reef ecosystems. PMID:21936880

Ferrari, Maud C O; McCormick, Mark I; Munday, Philip L; Meekan, Mark G; Dixson, Danielle L; Lonnstedt, Öona; Chivers, Douglas P

2011-09-21

36

Potential impact of low-concentration silver nanoparticles on predator-prey interactions between predatory dragonfly nymphs and Daphnia magna as a prey.  

PubMed

This study investigated the potential impacts of low-concentration citrate-coated silver nanoparticles (citrate-nAg; 2 ?g L(-1) as total Ag) on the interactions of Daphnia magna Straus (as a prey) with the predatory dragonfly ( Anax junius : Odonata) nymph using the behavioral, survival, and reproductive end points. Four different toxicity bioassays were evaluated: (i) horizontal migration; (ii) vertical migration; (iii) 48 h survival; and (iv) 21 day reproduction; using four different treatment combinations: (i) Daphnia + citrate-nAg; (ii) Daphnia + predator; (iii) Daphnia + citrate-nAg + predator; and (iv) Daphnia only (control). Daphnia avoided the predators using the horizontal and vertical movements, indicating that Daphnia might have perceived a significant risk of predation. However, with citrate-nAg + predator treatment, Daphnia response did not differ from control in the vertical migration test, suggesting that Daphnia were unable to detect the presence of predator with citrate-nAg treatment and this may have potential implication on daphnids population structure owing to predation risk. The 48 h survival test showed a significant mortality of Daphnia individuals in the presence of predators, with or without citrate-nAg, in the test environment. Average reproduction of daphnids increased by 185% with low-concentration citrate-nAg treatment alone but was severely compromised in the presence of predators (decreased by 91.3%). Daphnia reproduction was slightly enhanced by approximately 128% with citrate-nAg + predator treatment. Potential mechanisms of these differential effects of low-concentration citrate-nAg, with or without predators, are discussed. Because silver dissolution was minimal, the observed toxicity could not be explained by dissolved Ag alone. These findings offer novel insights into how exposure to low-concentration silver nanoparticles could influence predator-prey interactions in the fresh water systems. PMID:22697289

Pokhrel, Lok R; Dubey, Brajesh

2012-06-27

37

Spatial dynamics in a predator-prey model with herd behavior  

NASA Astrophysics Data System (ADS)

In this paper, a spatial predator-prey model with herd behavior in prey population and quadratic mortality in predator population is investigated. By the linear stability analysis, we obtain the condition for stationary pattern. Moreover, using standard multiple-scale analysis, we establish the amplitude equations for the excited modes, which determine the stability of amplitudes towards uniform and inhomogeneous perturbations. By numerical simulations, we find that the model exhibits complex pattern replication: spotted pattern, stripe pattern, and coexistence of the two. The results may enrich the pattern dynamics in predator-prey models and help us to better understand the dynamics of predator-prey interactions in a real environment.

Yuan, Sanling; Xu, Chaoqun; Zhang, Tonghua

2013-09-01

38

The effect of size on the fast-start performance of rainbow trout Salmo cairdneri, and a consideration of piscivorous predator-prey interactions.  

PubMed

The fast-start (acceleration) performance of seven groups of rainbow trout from 9-6 to 38-7 cm total length was measured in response to d.c. electric shock stimuli. Two fast-start kinematic patterns, L- and S-start were observed. In L-starts the body was bent into an L or U shape and a recoil turn normally accompanied acceleration. Free manoeuvre was not possible in L-starts without loss of speed. In S-starts the body was bent into an S-shape and fish accelerated without a recoil turn. The frequency of S-starts increased with size from 0 for the smallest fish to 60-65% for the largest fish. Acceleration turns were common. The radius of smallest turn for both fast-start patterns was proportional to length (L) with an overall radius of 0-17 L. The duration of the primary acceleration stages increased with size from 0-07 s for the group of smallest fish to 0-10 s for the group of largest fish. Acceleration rates were independent of size. The overall mean maximum rate was 3438 cm/s2 and the average value to the end of the primary acceleration movements was 1562 cm/s2. The distance covered and velocity attained after a given time for fish accelerating from rest were independent of size. The results are discussed in the context of interactions between a predator and prey fish following initial approach by the predator. It is concluded that the outcome of an interaction is likely to depend on reaction times of interacting fish responding to manoeuvres initiated by the predator or prey. The prey reaction time results in the performance of the predator exceeding that of the prey at any instant. The predator reaction time and predator error in responses to unpredictable prey manoeuvre are required for prey escape. It is predicted that a predator should strike the prey within 0-1 s if the fish are initially 5-15 cm apart as reported in the literature for predator-prey interactions. These distances would be increased for non-optimal prey escape behaviour and when the prey body was more compressed or depressed than the predator. PMID:993700

Webb, P W

1976-08-01

39

Effects of Temperature and Turbulence on the Predator–Prey Interactions between a Heterotrophic Flagellate and a Marine Bacterium  

Microsoft Academic Search

Biotic and abiotic factors can influence interactions between microbial grazers and their prey, thus impacting both the cycling of biogenic carbon within the surface layer of the ocean and the export of carbon to the deep ocean and higher trophic levels. In this study, microcosm experiments were used to evaluate the combined effect of temperature and turbulence on the growth

M. P. Delaney

2003-01-01

40

Interannual variability in a predator-prey interaction: climate, chaetognaths, and copepods in the southeastern Bering Sea  

Microsoft Academic Search

The interaction of the chaetognath Sagitta elegans with the copepod community of the southeast Bering Sea middle shelf was examined in relation to environmental conditions during 1995-1999. Predation impact was estimated for 2 years, 1995 and 1997, using gut content analysis, experimentally derived digestion time (DT) and abundances of chaetognaths and prey. Pseudoca- lanus concentrations correlated with water temperature and

C. T. Baier; M. TERAZAKI

2005-01-01

41

An experimental study on the effects of crayfish on the predator-prey interaction between bass and sculpin  

Microsoft Academic Search

1.We examined the hypothesis that in a one predator-two prey system, prey that share a common refuge might have indirect interactions mediated by their reciprocal effects on each other's refuge use. Our experiments were done in laboratory pools with plexiglas refuges, using predatory smallmouth bass, Micropterus dolemieui, that can consume crayfish, Orconectes putnami and mottled sculpin, Cottus bairdi.2.Bass consumed 35%

David L. McNeely; Brenda N. Futrell; Andrew Sih

1990-01-01

42

A predator-prey model with predators using hawk and dove tactics  

Microsoft Academic Search

In this work we present a predator-prey model that incorporates individual behavior of the predators. A classical Lotka-Volterra model with self-limiting prey describes the predator-prey interaction. Predator individuals can use two behavioral tactics to dispute a prey when they meet, the classical hawk and dove tactics. Each individual can use both tactics along its life. The predator behavioral change is

Pierre Auger; Rafael Bravo; Serge Morand

43

A predator–prey model with predators using hawk and dove tactics  

Microsoft Academic Search

In this work we present a predator–prey model that incorporates individual behavior of the predators. A classical Lotka–Volterra model with self-limiting prey describes the predator–prey interaction. Predator individuals can use two behavioral tactics to dispute a prey when they meet, the classical hawk and dove tactics. Each individual can use both tactics along its life. The predator behavioral change is

Pierre Auger; Rafael Bravo de la Parra; Serge Morand; Eva Sánchez

2002-01-01

44

Twospotted spider mite predator-prey model  

Microsoft Academic Search

This paper presents simulation models for the dynamics of a predator-prey system consisting of the twospotted spider mite Tetranychus urticae Koch as a prey and its predator Phytoseiulus persimilis Athias-Henriot. The percentage infestation of plant has been used as a basic unit for population densities of prey and predators. Parameter estimation has been done with the inclusion of diffusion and

Irina Kozlova; Manmohan Singh; Alan K. Easton; Peter Ridland

2005-01-01

45

Effect of resource subsidies on predator-prey population dynamics: a mathematical model.  

PubMed

The influence of a resource subsidy on predator-prey interactions is examined using a mathematical model. The model arises from the study of a biological system involving arctic foxes (predator), lemmings (prey), and seal carcasses (subsidy). In one version of the model, the predator, prey and subsidy all occur in the same location; in a second version, the predator moves between two patches, one containing only the prey and the other containing only the subsidy. Criteria for feasibility and stability of the different equilibrium states are studied both analytically and numerically. At small subsidy input rates, there is a minimum prey carrying capacity needed to support both predator and prey. At intermediate subsidy input rates, the predator and prey can always coexist. At high subsidy input rates, the prey cannot persist even at high carrying capacities. As predator movement increases, the dynamic stability of the predator-prey-subsidy interactions also increases. PMID:22877320

Nevai, Andrew L; Van Gorder, Robert A

2012-04-26

46

Predator-prey-substrate model of wastewater treatment in bioreactor system  

NASA Astrophysics Data System (ADS)

This paper analyses the mathematical model of the interaction between predator-prey and substrate that have been expressed as a system of nonlinear ordinary differential equations. This mathematical model can help to investigate the biological reaction of the interaction of predator-prey and substrate in biological wastewater treatment to improve the quality of water that flows out from the reactor. By using Monod Kinetics Growth Model, the steady state solutions have been obtained and their stability is determined as a function of the residence time.

Sadikin, Zubaidah; Salim, Normah; Allias, Razihan

2013-04-01

47

Predator-prey body size relationships when predators can consume prey larger than themselves.  

PubMed

As predator-prey interactions are inherently size-dependent, predator and prey body sizes are key to understanding their feeding relationships. To describe predator-prey size relationships (PPSRs) when predators can consume prey larger than themselves, we conducted field observations targeting three aquatic hemipteran bugs, and assessed their body masses and those of their prey for each hunting event. The data revealed that their PPSR varied with predator size and species identity, although the use of the averaged sizes masked these effects. Specifically, two predators had slightly decreased predator-prey mass ratios (PPMRs) during growth, whereas the other predator specialized on particular sizes of prey, thereby showing a clear positive size-PPMR relationship. We discussed how these patterns could be different from fish predators swallowing smaller prey whole. PMID:23536441

Nakazawa, Takefumi; Ohba, Shin-Ya; Ushio, Masayuki

2013-03-27

48

Stochastic population oscillations in spatial predator-prey models  

NASA Astrophysics Data System (ADS)

It is well-established that including spatial structure and stochastic noise in models for predator-prey interactions invalidates the classical deterministic Lotka-Volterra picture of neutral population cycles. In contrast, stochastic models yield long-lived, but ultimately decaying erratic population oscillations, which can be understood through a resonant amplification mechanism for density fluctuations. In Monte Carlo simulations of spatial stochastic predator-prey systems, one observes striking complex spatio-temporal structures. These spreading activity fronts induce persistent correlations between predators and prey. In the presence of local particle density restrictions (finite prey carrying capacity), there exists an extinction threshold for the predator population. The accompanying continuous non-equilibrium phase transition is governed by the directed-percolation universality class. We employ field-theoretic methods based on the Doi-Peliti representation of the master equation for stochastic particle interaction models to (i) map the ensuing action in the vicinity of the absorbing state phase transition to Reggeon field theory, and (ii) to quantitatively address fluctuation-induced renormalizations of the population oscillation frequency, damping, and diffusion coefficients in the species coexistence phase.

Täuber, Uwe C.

2011-09-01

49

Stochastic population oscillations in spatial predator-prey models  

NASA Astrophysics Data System (ADS)

It is well-established that including spatial structure and stochastic noise in models for predator-prey interactions invalidates the classical deterministic Lotka-Volterra picture of neutral population cycles. In contrast, stochastic models yield long-lived, but ultimately decaying erratic population oscillations, which can be understood through a resonant amplification mechanism for density fluctuations. In Monte Carlo simulations of spatial stochastic predator-prey systems, one observes striking complex spatio-temporal structures. These spreading activity fronts induce persistent correlations between predators and prey. In the presence of local particle density restrictions (finite prey carrying capacity), there exists an extinction threshold for the predator population. The accompanying continuous non-equilibrium phase transition is governed by the directed-percolation universality class. We employ field-theoretic methods based on the Doi-Peliti representation of the master equation for stochastic particle interaction models to (i) map the ensuing action in the vicinity of the absorbing state phase transition to Reggeon field theory, and (ii) to quantitatively address fluctuation-induced renormalizations of the population oscillation frequency, damping, and diffusion coefficients in the species coexistence phase. [See Preprint arXiv:1105.4242, and further refs. therein.

Tauber, Uwe C.

2011-10-01

50

Stochastic predator-prey models: spatial variability enhances species fitness  

NASA Astrophysics Data System (ADS)

It is now well understood that including spatial structure and stochastic noise in models for predator-prey interactions invalidates the classical deterministic Lotka-Volterra picture of neutral population cycles. In contrast, stochastic models yield long-lived, but ultimately decaying erratic population oscillations, which can be understood through a resonant amplification mechanism for density fluctuations. Simulations of spatial stochastic predator-prey systems yield striking complex spatio-temporal structures. These spreading activity fronts induce persistent correlations between predators and prey. Here, we address the influence of spatially varying reaction rates on a stochastic two-species Lotka-Volterra lattice model. The effects of this quenched randomness on population densities, transient oscillations, spatial correlations, and invasion fronts are investigated through Monte Carlo simulations. We find that spatial variability in the predation rate results in more localized activity patches. Population fluctuations in rare favorable regions in turn cause a remarkable increase in the asymptotic population densities of both predators and prey, and also lead to accelerated front propagation.

Tauber, Uwe C.

2009-03-01

51

Along Came a Spider: Using Live Arthropods in a Predator-Prey Activity  

ERIC Educational Resources Information Center

|We developed a predator-prey activity with eighth-grade students in which they used wolf spiders ("Lycosa carolinensis"), house crickets ("Acheta domestica"), and abiotic factors to address how (1) adaptations in predators and prey shape their interaction and (2) abiotic factors modify the interaction between predators and prey. We tested student…

Richardson, Matthew L.; Hari, Janice

2011-01-01

52

Evolution, Generality and Robustness of Emerged Surrounding Behavior in Continuous Predators-Prey Pursuit Problem  

Microsoft Academic Search

We present the result of our work on the use of strongly typed genetic programming with exception handling capabilities for the evolution of surrounding behavior of agents situated in an inherently cooperative envi- ronment. The predators-prey pursuit problem is used to verify our hypothesis that relatively complex surrounding behavior may emerge from simple, implicit, locally defined, and therefore—scalable interactions between

Ivan Tanev; Michael Brzozowski; Katsunori Shimohara

2005-01-01

53

Environmental versus demographic variability in stochastic predator–prey models  

NASA Astrophysics Data System (ADS)

In contrast to the neutral population cycles of the deterministic mean-field Lotka–Volterra rate equations, including spatial structure and stochastic noise in models for predator–prey interactions yields complex spatio-temporal structures associated with long-lived erratic population oscillations. Environmental variability in the form of quenched spatial randomness in the predation rates results in more localized activity patches. Our previous study showed that population fluctuations in rare favorable regions in turn cause a remarkable increase in the asymptotic densities of both predators and prey. Very intriguing features are found when variable interaction rates are affixed to individual particles rather than lattice sites. Stochastic dynamics with demographic variability in conjunction with inheritable predation efficiencies generate non-trivial time evolution for the predation rate distributions, yet with overall essentially neutral optimization.

Dobramysl, U.; Täuber, U. C.

2013-10-01

54

Aerosol-cloud-precipitation system as a predator-prey problem  

PubMed Central

We show that the aerosol–cloud–precipitation system exhibits characteristics of the predator-prey problem in the field of population dynamics. Both a detailed large eddy simulation of the dynamics and microphysics of a precipitating shallow boundary layer cloud system and a simpler model built upon basic physical principles, reproduce predator-prey behavior with rain acting as the predator and cloud as the prey. The aerosol is shown to modulate the predator-prey response. Steady-state solution to the proposed model shows the known existence of bistability in cloudiness. Three regimes are identified in the time-dependent solutions: (i) the weakly precipitating regime where cloud and rain coexist in a quasi steady state; (ii) the moderately drizzling regime where limit-cycle behavior in the cloud and rain fields is produced; and (iii) the heavily precipitating clouds where collapse of the boundary layer is predicted. The manifestation of predator-prey behavior in the aerosol–cloud–precipitation system is a further example of the self-organizing properties of the system and suggests that exploiting principles of population dynamics may help reduce complex aerosol–cloud–rain interactions to a more tractable problem.

Koren, Ilan; Feingold, Graham

2011-01-01

55

Aerosol-cloud-precipitation system as a predator-prey problem.  

PubMed

We show that the aerosol-cloud-precipitation system exhibits characteristics of the predator-prey problem in the field of population dynamics. Both a detailed large eddy simulation of the dynamics and microphysics of a precipitating shallow boundary layer cloud system and a simpler model built upon basic physical principles, reproduce predator-prey behavior with rain acting as the predator and cloud as the prey. The aerosol is shown to modulate the predator-prey response. Steady-state solution to the proposed model shows the known existence of bistability in cloudiness. Three regimes are identified in the time-dependent solutions: (i) the weakly precipitating regime where cloud and rain coexist in a quasi steady state; (ii) the moderately drizzling regime where limit-cycle behavior in the cloud and rain fields is produced; and (iii) the heavily precipitating clouds where collapse of the boundary layer is predicted. The manifestation of predator-prey behavior in the aerosol-cloud-precipitation system is a further example of the self-organizing properties of the system and suggests that exploiting principles of population dynamics may help reduce complex aerosol-cloud-rain interactions to a more tractable problem. PMID:21742979

Koren, Ilan; Feingold, Graham

2011-07-08

56

Phase transitions in predator-prey systems  

NASA Astrophysics Data System (ADS)

The relationship between predator and prey plays an important role in ecosystem conservation. However, our understanding of the principles underlying the spatial distribution of predators and prey is still poor. Here we present a phase diagram of a predator-prey system and investigate the lattice formation in such a system. We show that the production of stable lattice structures depends on the limited diffusion or migration of prey as well as higher carrying capacity for the prey. In addition, when the prey's growth rate is lower than the birth rate of the predator, global prey lattice formation is initiated by microlattices at the center of prey spirals. The predator lattice is later formed in the predator spirals. But both lattice formations proceed together as the prey growth rate increases.

Nagano, Seido; Maeda, Yusuke

2012-01-01

57

A synthetic Escherichia coli predator-prey ecosystem  

PubMed Central

We have constructed a synthetic ecosystem consisting of two Escherichia coli populations, which communicate bi-directionally through quorum sensing and regulate each other's gene expression and survival via engineered gene circuits. Our synthetic ecosystem resembles canonical predator–prey systems in terms of logic and dynamics. The predator cells kill the prey by inducing expression of a killer protein in the prey, while the prey rescue the predators by eliciting expression of an antidote protein in the predator. Extinction, coexistence and oscillatory dynamics of the predator and prey populations are possible depending on the operating conditions as experimentally validated by long-term culturing of the system in microchemostats. A simple mathematical model is developed to capture these system dynamics. Coherent interplay between experiments and mathematical analysis enables exploration of the dynamics of interacting populations in a predictable manner.

Balagadde, Frederick K; Song, Hao; Ozaki, Jun; Collins, Cynthia H; Barnet, Matthew; Arnold, Frances H; Quake, Stephen R; You, Lingchong

2008-01-01

58

Effects of rapid prey evolution on predator–prey cycles  

Microsoft Academic Search

We study the qualitative properties of population cycles in a predator–prey system where genetic variability allows contemporary\\u000a rapid evolution of the prey. Previous numerical studies have found that prey evolution in response to changing predation risk\\u000a can have major quantitative and qualitative effects on predator–prey cycles, including: (1) large increases in cycle period,\\u000a (2) changes in phase relations (so that

Laura E. Jones; Stephen P. Ellner

2007-01-01

59

Predator-prey model with prey-taxis and diffusion  

Microsoft Academic Search

The objective of this paper is to investigate the effect of prey-taxis on predator–prey models with Paramecium aurelia as the prey and Didinium nasutum as its predator. The logistic Lotka–Volterra predator–prey models with prey-taxis are solved numerically with four different response functions, two initial conditions and one data set. Routh–Hurwitz’s stability conditions are used to obtain the bifurcation values of

Aspriha Chakraborty; Manmohan Singh; David Lucy; Peter Ridland

2007-01-01

60

Predator-prey analitycal dinamics behavior using normal form method  

Microsoft Academic Search

Normal form theory is one important tool in local analysis of nonlinear dynamical systems near an equilibrium point. In this paper a systematic procedure based on normal form theory is proposed to investigate nonlinear effects arising from the perturbation model of the predator-prey dynamic model of Lotka Volterra. Using this method, a second-order model of the predator-prey is proposed in

I. Martinez; C. Juarez; P. M. Nancy J

2011-01-01

61

Coupled predator-prey oscillations in a chaotic food web.  

PubMed

Coupling of several predator-prey oscillations can generate intriguing patterns of synchronization and chaos. Theory predicts that prey species will fluctuate in phase if predator-prey cycles are coupled through generalist predators, whereas they will fluctuate in anti-phase if predator-prey cycles are coupled through competition between prey species. Here, we investigate predator-prey oscillations in a long-term experiment with a marine plankton community. Wavelet analysis of the species fluctuations reveals two predator-prey cycles that fluctuate largely in anti-phase. The phase angles point at strong competition between the phytoplankton species, but relatively little prey overlap among the zooplankton species. This food web architecture is consistent with the size structure of the plankton community, and generates highly dynamic food webs. Continued alternations in species dominance enable coexistence of the prey species through a non-equilibrium 'killing-the-winner' mechanism, as the system shifts back and forth between the two predator-prey cycles in a chaotic fashion. PMID:19845726

Benincà, Elisa; Jöhnk, Klaus D; Heerkloss, Reinhard; Huisman, Jef

2009-10-20

62

The interplay between density- and trait-mediated effects in predator-prey interactions: a case study in aphid wing polymorphism.  

PubMed

Natural enemies not only influence prey density but they can also cause the modification of traits in their victims. While such non-lethal effects can be very important for the dynamic and structure of prey populations, little is known about their interaction with the density-mediated effects of natural enemies. We investigated the relationship between predation rate, prey density and trait modification in two aphid-aphid predator interactions. Pea aphids (Acyrthosiphon pisum, Harris) have been shown to produce winged dispersal morphs in response to the presence of ladybirds or parasitoid natural enemies. This trait modification influences the ability of aphids to disperse and to colonise new habitats, and hence has a bearing on the population dynamics of the prey. In two experiments we examined wing induction in pea aphids as a function of the rate of predation when hoverfly larvae (Episyrphus balteatus) and lacewing larvae (Chrysoperla carnea) were allowed to forage in pea aphid colonies. Both hoverfly and lacewing larvae caused a significant increase in the percentage of winged morphs among offspring compared to control treatments, emphasising that wing induction in the presence of natural enemies is a general response in pea aphids. The percentage of winged offspring was, however, dependent on the rate of predation, with a small effect of predation on aphid wing induction at very high and very low predation rates, and a strong response of aphids at medium predation rates. Aphid wing induction was influenced by the interplay between predation rate and the resultant prey density. Our results suggests that density-mediated and trait-mediated effects of natural enemies are closely connected to each other and jointly determine the effect of natural enemies on prey population dynamics. PMID:12698353

Kunert, Grit; Weisser, Wolfgang W

2003-02-27

63

A Generic Approach for Obtaining Higher Entertainment in Predator\\/Prey Games  

Microsoft Academic Search

This paper constitutes a sequel to our previous work focused on investigating cooperative behaviors, adaptive learning and on-line interaction towards the generation of entertainment in computer games. A human-verified metric of interest (i.e. player entertainment) of predator\\/prey games and a neuro- evolution on-line learning (i.e. during play) approach are used to serve this purpose. Experiments presented here demonstrate the generality

Georgios N. Yannakakis; John Hallam

64

Matching allele dynamics and coevolution in a minimal predator prey replicator model  

NASA Astrophysics Data System (ADS)

A minimal Lotka Volterra type predator prey model describing coevolutionary traits among entities with a strength of interaction influenced by a pair of haploid diallelic loci is studied with a deterministic time continuous model. We show a Hopf bifurcation governing the transition from evolutionary stasis to periodic Red Queen dynamics. If predator genotypes differ in their predation efficiency the more efficient genotype asymptotically achieves lower stationary concentrations.

Sardanyés, Josep; Solé, Ricard V.

2008-01-01

65

Emergence of Oscillatory Turing Patterns Induced by Cross Diffusion in a Predator-Prey System  

NASA Astrophysics Data System (ADS)

In this paper, we presented a predator-prey model with self diffusion as well as cross diffusion. By using theory on linear stability, we obtain the conditions on Turing instability. The results of numerical simulations reveal that oscillating Turing patterns with hexagons arise in the system. And the values of the parameters we choose for simulations are outside of the Turing domain of the no cross diffusion system. Moreover, we show that cross diffusion has an effect on the persistence of the population, i.e., it causes the population to run a risk of extinction. Particularly, our results show that, without interaction with either a Hopf or a wave instability, the Turing instability together with cross diffusion in a predator-prey model can give rise to spatiotemporally oscillating solutions, which well enrich the finding of pattern formation in ecology.

Li, An-Wei; Jin, Zhen; Li, Li; Wang, Jian-Zhong

2012-12-01

66

A fluid mechanical model for mixing in a plankton predator-prey system  

NASA Astrophysics Data System (ADS)

A Lagrangian method is developed to study mixing of small particles in open flows. Particle Lagrangian Coherent Structures (pLCS) are identified as transport barriers in the dynamical systems of particles. We apply this method to a planktonic predator-prey system in which moon jellyfish Aurelia aurita uses its body motion to generate fluid currents which carry their prey to the vicinity of their capture appendages. With the flow generated by the jellyfish experimentally measured and the dynamics of prey particles in the flow described by a modified Maxey-Riley equation, we use pLCS to identify the capture region in which prey can be captured. The properties of the capture region enable analysis of the effects of several physiological and mechanical parameters on the predator-prey interaction, such as prey size, escape force, predator perception, etc. The method provides a new methodology to study dynamics and mixing of small organisms in general.

Peng, J.; Dabiri, J. O.

2009-04-01

67

Persistent predator-prey dynamics revealed by mass extinction  

PubMed Central

Predator–prey interactions are thought by many researchers to define both modern ecosystems and past macroevolutionary events. In modern ecosystems, experimental removal or addition of taxa is often used to determine trophic relationships and predator identity. Both characteristics are notoriously difficult to infer in the fossil record, where evidence of predation is usually limited to damage from failed attacks, individual stomach contents, one-sided escalation, or modern analogs. As a result, the role of predation in macroevolution is often dismissed in favor of competition and abiotic factors. Here we show that the end-Devonian Hangenberg event (359 Mya) was a natural experiment in which vertebrate predators were both removed and added to an otherwise stable prey fauna, revealing specific and persistent trophic interactions. Despite apparently favorable environmental conditions, crinoids diversified only after removal of their vertebrate consumers, exhibiting predatory release on a geological time scale. In contrast, later Mississippian (359–318 Mya) camerate crinoids declined precipitously in the face of increasing predation pressure from new durophagous fishes. Camerate failure is linked to the retention of obsolete defenses or “legacy adaptations” that prevented coevolutionary escalation. Our results suggest that major crinoid evolutionary phenomena, including rapid diversification, faunal turnover, and species selection, might be linked to vertebrate predation. Thus, interactions observed in small ecosystems, such as Lotka-Volterra cycles and trophic cascades, could operate at geologic time scales and higher taxonomic ranks. Both trophic knock-on effects and retention of obsolete traits might be common in the aftermath of predator extinction.

Sallan, Lauren Cole; Kammer, Thomas W.; Ausich, William I.; Cook, Lewis A.

2011-01-01

68

Spatiotemporal dynamics of the epidemic transmission in a predator-prey system.  

PubMed

Epidemic transmission is one of the critical density-dependent mechanisms that affect species viability and dynamics. In a predator-prey system, epidemic transmission can strongly affect the success probability of hunting, especially for social animals. Predators, therefore, will suffer from the positive density-dependence, i.e., Allee effect, due to epidemic transmission in the population. The rate of species contacting the epidemic, especially for those endangered or invasive, has largely increased due to the habitat destruction caused by anthropogenic disturbance. Using ordinary differential equations and cellular automata, we here explored the epidemic transmission in a predator-prey system. Results show that a moderate Allee effect will destabilize the dynamics, but it is not true for the extreme Allee effect (weak or strong). The predator-prey dynamics amazingly stabilize by the extreme Allee effect. Predators suffer the most from the epidemic disease at moderate transmission probability. Counter-intuitively, habitat destruction will benefit the control of the epidemic disease. The demographic stochasticity dramatically influences the spatial distribution of the system. The spatial distribution changes from oil-bubble-like (due to local interaction) to aggregated spatially scattered points (due to local interaction and demographic stochasticity). It indicates the possibility of using human disturbance in habitat as a potential epidemic-control method in conservation. PMID:18696164

Su, Min; Hui, Cang; Zhang, Yanyu; Li, Zizhen

2008-08-12

69

Using process algebra to develop predator-prey models of within-host parasite dynamics.  

PubMed

As a first approximation of immune-mediated within-host parasite dynamics we can consider the immune response as a predator, with the parasite as its prey. In the ecological literature of predator-prey interactions there are a number of different functional responses used to describe how a predator reproduces in response to consuming prey. Until recently most of the models of the immune system that have taken a predator-prey approach have used simple mass action dynamics to capture the interaction between the immune response and the parasite. More recently Fenton and Perkins (2010) employed three of the most commonly used prey-dependent functional response terms from the ecological literature. In this paper we make use of a technique from computing science, process algebra, to develop mathematical models. The novelty of the process algebra approach is to allow stochastic models of the population (parasite and immune cells) to be developed from rules of individual cell behaviour. By using this approach in which individual cellular behaviour is captured we have derived a ratio-dependent response similar to that seen in the previous models of immune-mediated parasite dynamics, confirming that, whilst this type of term is controversial in ecological predator-prey models, it is appropriate for models of the immune system. PMID:23499712

McCaig, Chris; Fenton, Andy; Graham, Andrea; Shankland, Carron; Norman, Rachel

2013-03-14

70

Quenched Spatial Disorder in Cyclic Three-Species Predator-Prey Models  

NASA Astrophysics Data System (ADS)

We employ individual-based Monte Carlo simulations to study the effects of quenched spatial disorder in the reaction rates on the co-evolutionary dynamics of cyclic three- species predator-prey models with conserved total particle density. To this end, we numerically explore the oscillatory dynamics of two different variants: (1) the model with symmetric interaction rates near the center of the configuration space, and (2) a strongly asymmetric model version located in one of the three ``corners'' of configuration space. We find that spatial rate variability has only minor effect on the dynamics of generic, not strongly asymmetric systems (variant 1). In stark contrast, spatial disorder can greatly enhance the fitness of both minor species in ``corner'' systems (2). Furthermore, through both mean-field analysis and numerical simulation, we conclude that the evolutionary dynamics of two-species Lotka-Volterra predator- prey models is well approximated by such strongly asymmetric cyclic three-species predator-prey systems. Refs.: Qian He, Mauro Mobilia, and Uwe C. Tauber, Phys. Rev. E 82, 051909 (2010); Qian He and Uwe C.Tauber, in preparation (2011).

He, Qian; Tauber, Uwe C.

2011-10-01

71

Effects of uniform rotational flow on predator–prey system  

NASA Astrophysics Data System (ADS)

Rotational flow is often observed in lotic ecosystems, such as streams and rivers. For example, when an obstacle interrupts water flowing in a stream, energy dissipation and momentum transfer can result in the formation of rotational flow, or a vortex. In this study, I examined how rotational flow affects a predator–prey system by constructing a spatially explicit lattice model consisting of predators, prey, and plants. A predation relationship existed between the species. The species densities in the model were given as S (for predator), P (for prey), and G (for plant). A predator (prey) had a probability of giving birth to an offspring when it ate prey (plant). When a predator or prey was first introduced, or born, its health state was assigned an initial value of 20 that subsequently decreased by one with every time step. The predator (prey) was removed from the system when the health state decreased to less than zero. The degree of flow rotation was characterized by the variable, R. A higher R indicates a higher tendency that predators and prey move along circular paths. Plants were not affected by the flow because they were assumed to be attached to the streambed. Results showed that R positively affected both predator and prey survival, while its effect on plants was negligible. Flow rotation facilitated disturbances in individuals' movements, which consequently strengthens the predator and prey relationship and prevents death from starvation. An increase in S accelerated the extinction of predators and prey.

Lee, Sang-Hee

2012-12-01

72

Identifying Predator–Prey Processes from Time-Series  

Microsoft Academic Search

The functional response is a key element in predator–prey models as well as in food chains and food webs. Classical models consider it as a function of prey abundance only. However, many mechanisms can lead to predator dependence, and there is increasing evidence for the importance of this dependence. Identification of the mathematical form of the functional response from real

Christian Jost; Roger Arditi

2000-01-01

73

Persistent predator-prey dynamics revealed by mass extinction.  

PubMed

Predator-prey interactions are thought by many researchers to define both modern ecosystems and past macroevolutionary events. In modern ecosystems, experimental removal or addition of taxa is often used to determine trophic relationships and predator identity. Both characteristics are notoriously difficult to infer in the fossil record, where evidence of predation is usually limited to damage from failed attacks, individual stomach contents, one-sided escalation, or modern analogs. As a result, the role of predation in macroevolution is often dismissed in favor of competition and abiotic factors. Here we show that the end-Devonian Hangenberg event (359 Mya) was a natural experiment in which vertebrate predators were both removed and added to an otherwise stable prey fauna, revealing specific and persistent trophic interactions. Despite apparently favorable environmental conditions, crinoids diversified only after removal of their vertebrate consumers, exhibiting predatory release on a geological time scale. In contrast, later Mississippian (359-318 Mya) camerate crinoids declined precipitously in the face of increasing predation pressure from new durophagous fishes. Camerate failure is linked to the retention of obsolete defenses or "legacy adaptations" that prevented coevolutionary escalation. Our results suggest that major crinoid evolutionary phenomena, including rapid diversification, faunal turnover, and species selection, might be linked to vertebrate predation. Thus, interactions observed in small ecosystems, such as Lotka-Volterra cycles and trophic cascades, could operate at geologic time scales and higher taxonomic ranks. Both trophic knock-on effects and retention of obsolete traits might be common in the aftermath of predator extinction. PMID:21536875

Sallan, Lauren Cole; Kammer, Thomas W; Ausich, William I; Cook, Lewis A

2011-05-02

74

A diffusive predator–prey model with a protection zone  

Microsoft Academic Search

In this paper we study the effects of a protection zone ?0 for the prey on a diffusive predator–prey model with Holling type II response and no-flux boundary condition. We show the existence of a critical patch size described by the principal eigenvalue ?1D(?0) of the Laplacian operator over ?0 with homogeneous Dirichlet boundary conditions. If the protection zone is

Yihong Du; Junping Shi

2006-01-01

75

Potential landscape and probabilistic flux of a predator prey network.  

PubMed

Predator-prey system, as an essential element of ecological dynamics, has been recently studied experimentally with synthetic biology. We developed a global probabilistic landscape and flux framework to explore a synthetic predator-prey network constructed with two Escherichia coli populations. We developed a self consistent mean field method to solve multidimensional problem and uncovered the potential landscape with Mexican hat ring valley shape for predator-prey oscillations. The landscape attracts the system down to the closed oscillation ring. The probability flux drives the coherent oscillations on the ring. Both the landscape and flux are essential for the stable and coherent oscillations. The landscape topography characterized by the barrier height from the top of Mexican hat to the closed ring valley provides a quantitative measure of global stability of system. The entropy production rate for the energy dissipation is less for smaller environmental fluctuations or perturbations. The global sensitivity analysis based on the landscape topography gives specific predictions for the effects of parameters on the stability and function of the system. This may provide some clues for the global stability, robustness, function and synthetic network design. PMID:21423576

Li, Chunhe; Wang, Erkang; Wang, Jin

2011-03-15

76

The Influence of Predator–Prey Population Dynamics on the Long-term Evolution of Food Web Structure  

Microsoft Academic Search

We develop a set of equations to describe the population dynamics of many interacting species in food webs. Predator–prey interactions are nonlinear, and are based on ratio-dependent functional responses. The equations account for competition for resources between members of the same species, and between members of different species. Predators divide their total hunting\\/foraging effort between the available prey species according

BARBARA DROSSEL; PAUL G. HIGGS; ALAN J. MCKANE

2001-01-01

77

Investigations of Multidimensional Predator-Prey Models  

Microsoft Academic Search

The Gause-Lotka-Volterra (GLV) equations are an idealized model for competition between n species. The n-RPS and May Leonard competing species models are specific cases of (GLV) which define interaction between various species differently. n-RPS couples n equations in a ?Rock-Paper-Scissors? (RPS)-type relation in which each species has both a unique predator and prey such that the n species interact with

Ariel Krasik-Geiger

2009-01-01

78

Deer Me: A Predator/Prey Simulation  

NSDL National Science Digital Library

In this activity, learners will simulate the interactions between a predator population of gray wolves and a prey population of deer in a forest. After collecting the data, the learners plot the data and then extend the graph to predict the populations for several more generations.

Zoo, Minnesota; Eduweb

2012-01-01

79

Simple predator-prey swarming model  

NASA Astrophysics Data System (ADS)

This paper describes an individual-based model for simulating the swarming behavior of prey in the presence of predators. Predators and prey are represented as agents that interact through radial force laws. The prey form swarms through attractive and repulsive forces. The predators interact with the prey through an anti-Newtonian force, which is a nonconservative force that acts in the same direction for both agents. Several options for forces between predators are explored. The resulting equations are solved numerically and the dynamics are described in the context of the swarm’s ability to realistically avoid the predators. The goal is to reproduce swarm behavior that has been observed in nature with the simplest possible model.

Zhdankin, Vladimir; Sprott, J. C.

2010-11-01

80

Impacts of biotic resource enrichment on a predator-prey population.  

PubMed

The environmental carrying capacity is usually assumed to be fixed quantity in the classical predator-prey population growth models. However, this assumption is not realistic as the environment generally varies with time. In a bid for greater realism, functional forms of carrying capacities have been widely applied to describe varying environments. Modelling carrying capacity as a state variable serves as another approach to capture the dynamical behavior between population and its environment. The proposed modified predator-prey model is based on the ratio-dependent models that have been utilized in the study of food chains. Using a simple non-linear system, the proposed model can be linked to an intra-guild predation model in which predator and prey share the same resource. Distinct from other models, we formulate the carrying capacity proportional to a biotic resource and both predator and prey species can directly alter the amount of resource available by interacting with it. Bifurcation and numerical analyses are presented to illustrate the system's dynamical behavior. Taking the enrichment parameter of the resource as the bifurcation parameter, a Hopf bifurcation is found for some parameter ranges, which generate solutions that posses limit cycle behavior. PMID:23864218

Safuan, H M; Sidhu, H S; Jovanoski, Z; Towers, I N

2013-07-18

81

Plugging space into predator-prey models: an empirical approach.  

PubMed

Extrapolating ecological processes from small-scale experimental systems to scales of natural populations usually entails a considerable increase in spatial heterogeneity, which may affect process rates and, ultimately, population dynamics. We demonstrate how information on the heterogeneity of natural populations can be taken into account when scaling up laboratory-derived process functions, using the technique of moment approximation. We apply moment approximation to a benthic crustacean predator-prey system, where a laboratory-derived functional response is made spatial by including correction terms for the variance in prey density and the covariance between prey and predator densities observed in the field. We also show how moment approximation may be used to incorporate spatial information into a dynamic model of the system. While the nonspatial model predicts stable dynamics, its spatial equivalent also produces bounded fluctuations, in agreement with observed dynamics. A detailed analysis shows that predator-prey covariance, but not prey variance, destabilizes the dynamics. We conclude that second-order moment approximation may provide a useful technique for including spatial information in population models. The main advantage of the method is its conceptual value: by providing explicit estimates of variance and covariance effects, it offers the possibility of understanding how heterogeneity affects ecological processes. PMID:16670984

Bergström, Ulf; Englund, Göran; Leonardsson, Kjell

2006-01-09

82

Short-term sublethal hypoxia affects a predator-prey system in northern Adriatic transitional waters  

NASA Astrophysics Data System (ADS)

Predation intensity depends on factors that affect both the predator’s ability to locate prey as well as defensive responses by prey to approaching predators. The interactive effects of short-term hypoxia and predation were tested on the survival of two bivalves (Tapes philippinarum and Musculista senhousia) through laboratory experiments using the crab Carcinus aestuarii as predator. We found M. senhousia to be a focal prey of C. aestuarii but, after non-lethal hypoxia, the crabs’ preference for the focal prey was influenced by the presence of the other prey, T. philippinarum. We observed an environmentally-mediated, non-reciprocal indirect interaction between the two prey species, probably caused by differences in specific traits. Identifying the influence of short-term disturbance on predator-prey relationships is critical for predicting the effects of changes in water quality on trophic interactions and food web dynamics in transitional systems.

Munari, Cristina; Mistri, Michele

2012-01-01

83

Predator-prey pursuit-evasion games in structurally complex environments.  

PubMed

Pursuit and evasion behaviors in many predator-prey encounters occur in a geometrically structured environment. The physical structures in the environment impose strong constraints on the perception and behavioral responses of both antagonists. Nevertheless, no experimental or theoretical study has tackled the issue of quantifying the role of the habitat's architecture on the joint trajectories during a predator-prey encounter. In this study, we report the influence of microtopography of forest leaf litter on the pursuit-evasion trajectories of wolf spiders Pardosa sp. attacking the wood cricket Nemobius sylvestris. Fourteen intact leaf litter samples of 1 m × 0.5 m were extracted from an oak-beech forest floor in summer and winter, with later samples having the most recently fallen leaves. Elevation was mapped at a spatial resolution of 0.5 mm using a laser scanner. Litter structuring patterns were identified by height transects and experimental semi-variograms. Detailed analysis of all visible leaf-fragments of one sample enabled us to relate the observed statistical patterns to the underlying geometry of individual elements. Video recording of pursuit-evasion sequences in arenas with flat paper or leaf litter enabled us to estimate attack and fleeing distances as a function of substrate. The compaction index, the length of contiguous flat surfaces, and the experimental variograms showed that the leaf litter was smoother in summer than in winter. Thus, weathering as well as biotic activities compacted and flattened the litter over time. We found good agreement between the size of the structuring unit of leaf litter and the distance over which attack and escape behaviors both were initiated (both ?3 cm). There was a four-fold topographical effect on pursuit-escape sequences; compared with a flat surface, leaf litter (1) greatly reduced the likelihood of launching a pursuit, (2) reduced pursuit and escape distances by half, (3) put prey and predator on par in terms of pursuit and escape distances, and (4) reduced the likelihood of secondary pursuits, after initial escape of the prey, to nearly zero. Thus, geometry of the habitat strongly modulates the rules of pursuit-evasion in predator-prey interactions in the wild. PMID:23720527

Morice, Sylvie; Pincebourde, Sylvain; Darboux, Frédéric; Kaiser, Wilfried; Casas, Jérôme

2013-05-28

84

Fluctuation-driven Turing patterns in predator-prey dynamics  

NASA Astrophysics Data System (ADS)

Models of diffusion-driven pattern formation that rely on the Turing mechanism are utilized in many areas of science. However, many such models suffer from the defect of requiring fine tuning of parameters or an unrealistic separation of scales in the diffusivities of the constituents of the system in order to predict the formation of spatial patterns. In the context of a generic model of predator-prey population dynamics, we show that the inclusion of intrinsic noise in Turing models leads to the formation of ``quasipatterns'' that form in generic regions of parameter space and are experimentally distinguishable from standard Turing patterns. The existence of quasipatterns removes the need for unphysical fine tuning or separation of scales in the application of Turing models to real systems. We also exhibit numerical simulations of the formation of quasi-patterns deep in the quasi-pattern phase.

Butler, Thomas; Goldenfeld, Nigel

2012-02-01

85

On the Neimark-Sacker bifurcation in a discrete predator-prey system.  

PubMed

A two-parameter family of discrete models describing a predator-prey interaction is considered, which generalizes a model discussed by Murray, and originally due to Nicholson and Bailey, consisting of two coupled nonlinear difference equations. In contrast to the original case treated by Murray, where the two populations either die out or may display unbounded growth, the general member of this family displays a somewhat wider range of behaviour. In particular, the model has a nontrivial steady state which is stable for a certain range of parameter values, which is explicitly determined, and also undergoes a Neimark-Sacker bifurcation that produces an attracting invariant curve in some areas of the parameter space and a repelling one in others. PMID:22881206

Hone, A N W; Irle, M V; Thurura, G W

2010-11-01

86

Predator-Prey Dynamics Driven by Feedback between Functionally Diverse Trophic Levels  

PubMed Central

Neglecting the naturally existing functional diversity of communities and the resulting potential to respond to altered conditions may strongly reduce the realism and predictive power of ecological models. We therefore propose and study a predator-prey model that describes mutual feedback via species shifts in both predator and prey, using a dynamic trait approach. Species compositions of the two trophic levels were described by mean functional traits—prey edibility and predator food-selectivity—and functional diversities by the variances. Altered edibility triggered shifts in food-selectivity so that consumers continuously respond to the present prey composition, and vice versa. This trait-mediated feedback mechanism resulted in a complex dynamic behavior with ongoing oscillations in the mean trait values, reflecting continuous reorganization of the trophic levels. The feedback was only possible if sufficient functional diversity was present in both trophic levels. Functional diversity was internally maintained on the prey level as no niche existed in our system, which was ideal under any composition of the predator level due to the trade-offs between edibility, growth and carrying capacity. The predators were only subject to one trade-off between food-selectivity and grazing ability and in the absence of immigration, one predator type became abundant, i.e., functional diversity declined to zero. In the lack of functional diversity the system showed the same dynamics as conventional models of predator-prey interactions ignoring the potential for shifts in species composition. This way, our study identified the crucial role of trade-offs and their shape in physiological and ecological traits for preserving diversity.

Wirtz, Kai; Gaedke, Ursula

2011-01-01

87

Use of Cobra Lily (Darlingtonia californica) & Drosophila for Investigating Predator-Prey Relationships.  

ERIC Educational Resources Information Center

|Describes an experiment that uses the cobra lily (Darlingtonia californica) and fruit flies (Drosophila virilis) to investigate predator-prey relationships in a classroom laboratory. Suggestions for classroom extension of this experimental system are provided. (ZWH)|

Pratt, Carl R.

1994-01-01

88

Are Classical Predator–Prey Models Relevant to the Real World?  

Microsoft Academic Search

Mathematical models of predator–prey population dynamics are widely used for predicting the effect of predators as biocontrol agents, but the assumptions of the models are more relevant to parasite–host systems. Predator–prey systems, at least in insects, substantially differ from what is assumed by these models. The main differences are: (i) Juveniles and adults have to be considered as two different

IVA DOSTÁLKOVÁ; PAVEL KINDLMANN; ANTHONY F. G. DIXON

2002-01-01

89

EFFECT OF PREY-TAXIS ON THE PERIODICITY OF PREDATOR-PREY DYNAMICS  

Microsoft Academic Search

The aim of this paper is to observe the ef- fect of prey-taxis on the periodicity of predator-prey dynam- ics. The logistic Lotka-Volterra predator-prey-taxis equations with diusion and advection are solved numerically using two dieren t response functions with two data sets and two non- homogeneous initial conditions. We show that for dieren t val- ues of prey-taxis it is

ASPRIHA CHAKRABORTY; MANMOHAN SINGH

90

The scaling of locomotor performance in predator–prey encounters: from fish to killer whales  

Microsoft Academic Search

During predator–prey encounters, a high locomotor performance in unsteady manoeuvres (i.e. acceleration, turning) is desirable for both predators and prey. While speed increases with size in fish and other aquatic vertebrates in continuous swimming, the speed achieved within a given time, a relevant parameter in predator–prey encounters, is size independent. In addition, most parameters indicating high performance in unsteady swimming

Paolo Domenici

2001-01-01

91

Reentrant phase transition in a predator-prey model  

NASA Astrophysics Data System (ADS)

We numerically investigate the six-species predator-prey game in complex networks as well as in d -dimensional regular hypercubic lattices with d=1,2,…,6 . The food-web topology of the six species contains two directed loops, each of which is composed of cyclically predating three species. As the mutation rate is lowered below the well-defined phase transition point, the Z2 symmetry related with the interchange in the two loops is spontaneously broken, and it has been known that the system develops the defensive alliance in which three cyclically predating species defend each other against the invasion of other species. In the Watts-Strogatz small-world network structure characterized by the rewiring probability ? , the phase diagram shows the reentrant behavior as ? is varied, indicating a twofold role of the shortcuts. In d -dimensional regular hypercubic lattices, the system also exhibits the reentrant phase transition as d is increased. We identify universality class of the phase transition and discuss the proper mean-field limit of the system.

Han, Sung-Guk; Park, Su-Chan; Kim, Beom Jun

2009-06-01

92

On the relationship between cyclic and hierarchical three-species predator-prey systems and the two-species Lotka-Volterra model  

Microsoft Academic Search

We aim to clarify the relationship between interacting three-species models and the two-species Lotka-Volterra (LV) model. We utilize mean-field theory and Monte Carlo simulations on two-dimensional square lattices to explore the temporal evolution characteristics of two different interacting three-species predator-prey systems: (1) a cyclic rock-paper-scissors (RPS) model with conserved total particle number but strongly asymmetric reaction rates that lets the

Qian He; Uwe C. Tauber; R. K. P. Zia

2011-01-01

93

Human Activity Helps Prey Win the Predator-Prey Space Race  

PubMed Central

Predator-prey interactions, including between large mammalian wildlife species, can be represented as a “space race”, where prey try to minimize and predators maximize spatial overlap. Human activity can also influence the distribution of wildlife species. In particular, high-human disturbance can displace large carnivore predators, a trait-mediated direct effect. Predator displacement by humans could then indirectly benefit prey species by reducing predation risk, a trait-mediated indirect effect of humans that spatially decouples predators from prey. The purpose of this research was to test the hypothesis that high-human activity was displacing predators and thus indirectly creating spatial refuge for prey species, helping prey win the “space race”. We measured the occurrence of eleven large mammal species (including humans and cattle) at 43 camera traps deployed on roads and trails in southwest Alberta, Canada. We tested species co-occurrence at camera sites using hierarchical cluster and nonmetric multidimensional scaling (NMS) analyses; and tested whether human activity, food and/or habitat influenced predator and prey species counts at camera sites using regression tree analysis. Cluster and NMS analysis indicated that at camera sites humans co-occurred with prey species more than predator species and predator species had relatively low co-occurrence with prey species. Regression tree analysis indicated that prey species were three times more abundant on roads and trails with >32 humans/day. However, predators were less abundant on roads and trails that exceeded 18 humans/day. Our results support the hypothesis that high-human activity displaced predators but not prey species, creating spatial refuge from predation. High-human activity on roads and trails (i.e., >18 humans/day) has the potential to interfere with predator-prey interactions via trait-mediated direct and indirect effects. We urge scientist and managers to carefully consider and quantify the trait-mediated indirect effects of humans, in addition to direct effects, when assessing human impacts on wildlife and ecosystems.

Muhly, Tyler B.; Semeniuk, Christina; Massolo, Alessandro; Hickman, Laura; Musiani, Marco

2011-01-01

94

Human activity helps prey win the predator-prey space race.  

PubMed

Predator-prey interactions, including between large mammalian wildlife species, can be represented as a "space race", where prey try to minimize and predators maximize spatial overlap. Human activity can also influence the distribution of wildlife species. In particular, high-human disturbance can displace large carnivore predators, a trait-mediated direct effect. Predator displacement by humans could then indirectly benefit prey species by reducing predation risk, a trait-mediated indirect effect of humans that spatially decouples predators from prey. The purpose of this research was to test the hypothesis that high-human activity was displacing predators and thus indirectly creating spatial refuge for prey species, helping prey win the "space race". We measured the occurrence of eleven large mammal species (including humans and cattle) at 43 camera traps deployed on roads and trails in southwest Alberta, Canada. We tested species co-occurrence at camera sites using hierarchical cluster and nonmetric multidimensional scaling (NMS) analyses; and tested whether human activity, food and/or habitat influenced predator and prey species counts at camera sites using regression tree analysis. Cluster and NMS analysis indicated that at camera sites humans co-occurred with prey species more than predator species and predator species had relatively low co-occurrence with prey species. Regression tree analysis indicated that prey species were three times more abundant on roads and trails with >32 humans/day. However, predators were less abundant on roads and trails that exceeded 18 humans/day. Our results support the hypothesis that high-human activity displaced predators but not prey species, creating spatial refuge from predation. High-human activity on roads and trails (i.e., >18 humans/day) has the potential to interfere with predator-prey interactions via trait-mediated direct and indirect effects. We urge scientist and managers to carefully consider and quantify the trait-mediated indirect effects of humans, in addition to direct effects, when assessing human impacts on wildlife and ecosystems. PMID:21399682

Muhly, Tyler B; Semeniuk, Christina; Massolo, Alessandro; Hickman, Laura; Musiani, Marco

2011-03-02

95

Phase Transitions and Fluctuations in Lattice Predator-Prey Models with Site Restrictions  

NASA Astrophysics Data System (ADS)

Studying the effects of spatial constraints and stochastic fluctuations on a class of predator-prey models with two species defined on a lattice it has been shown that the celebrated Lotka-Volterra's mean-field rate equation picture is invalidated. In this contribution, we report how site occupation constraints, modeling locally limited resources and the range of the interaction between species can lead to the emergence of an active-to-absorbing phase transition or to a first order phase transition. In particular, ecologically motivated models with nearest and next-nearest neighbor interactions are discussed and shown to display both an absorbing and an active steady state. In the latter case, where predators and prey coexist, the classical limit cycles or centers are replaced by either nodes or foci, leading to damped oscillatory behavior of the densities of predators and prey in the thermodynamic limit and to stationary configuration displaying complex spatiotemporal patterns. We discuss the validity of the analytic approach against numerical simulations and the subtle role played by the fluctuations and by the degree of ``stirring'' of the system.

Mobilia, Mauro

2005-03-01

96

Predator prey oscillations in a simple cascade model of drift wave turbulence  

NASA Astrophysics Data System (ADS)

A reduced three shell limit of a simple cascade model of drift wave turbulence, which emphasizes nonlocal interactions with a large scale mode, is considered. It is shown to describe both the well known predator prey dynamics between the drift waves and zonal flows and to reduce to the standard three wave interaction equations. Here, this model is considered as a dynamical system whose characteristics are investigated. The analytical solutions for the purely nonlinear limit are given in terms of the Jacobi elliptic functions. An approximate analytical solution involving Jacobi elliptic functions and exponential growth is computed using scale separation for the case of unstable solutions that are observed when the energy injection rate is high. The fixed points of the system are determined, and the behavior around these fixed points is studied. The system is shown to display periodic solutions corresponding to limit cycle oscillations, apparently chaotic phase space orbits, as well as unstable solutions that grow slowly while oscillating rapidly. The period doubling route to transition to chaos is examined.

Berionni, V.; Gürcan, Ö. D.

2011-11-01

97

Threshold policies control for predator-prey systems using a control Liapunov function approach.  

PubMed

The stability of predator-prey models, in the context of exploitation of renewable resources, subject to threshold policies (TP) is studied in this paper using the idea of backstepping and control Liapunov functions (CLF) well known in control theory, as well as the concept of virtual equilibria. TPs are defined and analysed for different types of one and two species predator-prey models. The models studied are the single species Noy-Meir herbivore-vegetation model, in a grazing management context, as well as the Rosenzweig-MacArthur two species predator-prey model, in a fishery management context. TPs are shown to be versatile and useful in managing renewable resources, being simple to design and implement, and also yielding advantages in situations of overexploitation. PMID:15888305

Meza, Magno Enrique Mendoza; Bhaya, Amit; Kaszkurewicz, Eugenius; da Silveira Costa, Michel Iskin

2005-06-01

98

Spatially induced speciation prevents extinction: the evolution of dispersal distance in oscillatory predator-prey models.  

PubMed Central

In a discrete-generation, individual-oriented model of predator-prey interactions that exhibits oscillations, we show that the self-structuring of the populations into spiral waves induces a selection pressure for ever-increasing dispersal distances in both populations. As the dispersal distances increase, the sizes of the spatial patterns increase, until they are too large to fit into the limited space. The patterns are then lost and the predators go extinct. This scenario, is, however, not the only outcome. A second selection pressure induced by the spatial boundary can cause reduction of the dispersal distances. Depending on the relative strengths of the two selection pressures, the predators and prey may speciate to give coexistence between short-dispersing boundary quasi-species and far-dispersing spiral quasi-species. Now, when pattern loss occurs, the predators switch to predating on the boundary prey quasi-species and do not go extinct. Also, if the populations reproduce sexually, local gene flow can inhibit the evolution of increasing dispersal distances, and hence the spatial patterns are not lost. Speciation and coexistence can also occur in the sexually reproducing species.

Savill, N J; Hogeweg, P

1998-01-01

99

Pattern formation in a predator–prey model with spatial effect  

NASA Astrophysics Data System (ADS)

In this paper, spatial dynamics in the Beddington–DeAngelis predator–prey model with self-diffusion and cross-diffusion is investigated. We analyze the linear stability and obtain the condition of Turing instability of this model. Moreover, we deduce the amplitude equations and determine the stability of different patterns. Numerical simulations show that this system exhibits complex dynamical behaviors. In the Turing space, we find three types of typical patterns. One is the coexistence of hexagon patterns and stripe patterns. The other two are hexagon patterns of different types. The obtained results well enrich the finding in predator–prey models with Beddington–DeAngelis functional response.

Xue, Lin

2012-12-01

100

Predator-prey interactions, resource depression and patch revisitation  

USGS Publications Warehouse

Generalist predators may be confronted by different types of prey in different patches: sedentary and conspicuous, cryptic (with or without refugia), conspicuous and nonsocial, or conspicuous and social. I argue that, where encounter rates with prey are of most importance, patch revisitation should be a profitable tactic where prey have short 'recovery' times (conspicuous, nonsocial prey), or where anti-predator response (e.g. shoaling) may increase conspicuousness. Predictions are made for how temporal changes in prey encounter rates should affect revisit schedules and feeding rates for the 4 different prey types.

Erwin, R.M.

1989-01-01

101

Predator-prey interactions between Orius insidiosus and flower thrips  

Technology Transfer Automated Retrieval System (TEKTRAN)

The great debates generated in Australia some 50 years ago regarding the relative merits of density dependent versus density independent forces in population dynamics were both reiterations of earlier ecological debates and precursors of succeeding ones. Perhaps, as has been recently emphasised, the...

102

The study of cooperative behavior in predator-prey problem of multi-agent systems  

Microsoft Academic Search

An important study in multi-agent systems is the development of cooperative behavior between agents that have a shared goal. In this paper, an example of the predator-prey problem is studied in which four predator agents, using the reinforcement learning method, in an attempt to collectively achieve the task of surrounding one prey agent. First, we describe the structure of the

Duo Zhao; WeiDong Jin

2005-01-01

103

Don't move: the T-Rex effect in the predator-prey world  

Microsoft Academic Search

To develop robust agents capable of adapting to changes in environment conditions we analyze the effects of introducing noise into multi-agent communication and varying prey movement patterns in a version of the predator-prey pursuit problem. In this simulation, predators communicate with languages evolved using a genetic algorithm. We show the time it takes to capture prey increases as more noise

Todd M. Bacastow; Brian R. Cook; Kam-Chuen Jim; C. Lee Giles

2003-01-01

104

Landscape heterogeneity shapes predation in a newly restored predator?prey system  

Microsoft Academic Search

Because some native ungulates have lived without top predators for generations, it has been uncertain whether runaway predation would occur when predators are newly restored to these systems. We show that landscape features and vegetation, which influence predator detection and capture of prey, shape large-scale patterns of predation in a newly restored predator-prey system. We analysed the spatial distribution of

Matthew J. Kauffman; Nathan Varley; Douglas W. Smith; Daniel R. Stahler; Daniel R. MacNulty; Mark S. Boyce

2007-01-01

105

Bionomic Exploitation of a Ratio-Dependent Predator-Prey System  

ERIC Educational Resources Information Center

|The present article deals with the problem of combined harvesting of a Michaelis-Menten-type ratio-dependent predator-prey system. The problem of determining the optimal harvest policy is solved by invoking Pontryagin's Maximum Principle. Dynamic optimization of the harvest policy is studied by taking the combined harvest effort as a dynamic…

Maiti, Alakes; Patra, Bibek; Samanta, G. P.

2008-01-01

106

Predator-prey analysis of striped bass and Atlantic menhaden in upper Chesapeake Bay  

Microsoft Academic Search

Between 1997 and 2000, an outbreak of skin lesions and observations of emaciated striped bass, Morone saxatilis (Walbaum), in upper Chesapeake Baywere attributed to a perceived shortage of its main prey , Atlantic menhaden, Brevoortia tyrannus Latrobe. Abundance estimates, Atlantic menhaden consumption per recruit analysis (modified yield-per-recruit), bioenergetics analysis and predator-prey theory were combined to explore whether an imbalance between

J. H. U PHOFF

2003-01-01

107

Periodic Solutions of Nonautonomous Discrete Predator-Prey System of Lotka-Volterra Type  

Microsoft Academic Search

A sufficiency criterion is established for the existence of positive periodic solutions of a nonautonomous discrete time predator-prey system of Lotka-Volterra type. Our approach is based on the coincidence degree and the related continuation theorem as well as some priori estimates.

Meng Fan; Sheba Agarwal

2002-01-01

108

Emotional versus non-Emotional Agents in a predator-prey environment  

Microsoft Academic Search

This paper discusses the dierences in performance and be- havior of emotional and non-emotional agents in a predator- prey environment. Using the prototypes of van Kesteren(vK01) and Burgh- outs(Bur02) it was concluded that while the behavior of the emotional agents is more believable, emotions also neg- atively influences the performance of the agents.

Herman Stehouwer

109

Permanence and global attractivity of a periodic predator-prey system with mutual interference and impulses  

NASA Astrophysics Data System (ADS)

In this paper, we consider a periodic predator-prey system with mutual interference and impulses. By constructing a suitable Lyapunov function and using the comparison theorem of impulsive differential equation, sufficient conditions which ensure the permanence and global attractivity of the system are obtained. We also present some examples to verify our main results.

Li, Zhong; Chen, Fengde; He, Mengxin

2012-01-01

110

A stage structured predator-prey model and its dependence on maturation delay and death rate  

Microsoft Academic Search

Many of the existing models on stage structured populations are single species models or models which assume a constant resource supply. In reality, growth is a combined result of birth and death processes, both of which are closely linked to the resource supply which is dynamic in nature. From this basic standpoint, we formulate a general and robust predator-prey model

Stephen A. Gourley; Yang Kuang

2004-01-01

111

Permanence of a predator-prey system with stage structure and time delay  

Microsoft Academic Search

A stage-structured predator–prey system (stage structure for both predator and prey) with discrete time delay has been presented in this paper. By analyzing the model and using the standard comparison theorem, the sufficient conditions are derived for permanence of the system and non-permanence of predators.

Zhi-hui Ma; Zi-zhen Li; Shu-fan Wang; Ting Li; Feng-pan Zhang

2008-01-01

112

Modelling a predator–prey system with infected prey in polluted environment  

Microsoft Academic Search

A predator–prey model with logistic growth in prey is modified by introducing an SIS parasite infection in the prey. We have studied the combined effect of environmental toxicant and disease on prey–predator system. It is assumed in this paper that the environmental toxicant affects both prey and predator population and the infected prey is assumed to be more vulnerable to

Sudipa Sinha; O. P. Misra; J. Dhar

2010-01-01

113

Evolution of body size, range size, and food composition in a predator–prey metapopulation  

Microsoft Academic Search

Relationships among body size, range size, and food composition are central to community ecology. Utilizing a simple framework of allopatric speciation, a stochastic, cellular automaton model of predator–prey metapopulations in one- and two-dimensional patchy networks are constructed. In the model, ecological processes, such as local extinction, recolonization, and predation, and evolutionary processes, such as mutation, influence the average body size

C. Hui; M. A. McGeoch

2006-01-01

114

A predator–prey model with disease in the predator species only  

Microsoft Academic Search

In this paper we propose a predator–prey model with logistic growth in the prey population that includes an SIS parasitic infection in the predator population, with the assumption that the predator has an alternative source of food. For simplicity we initially work with a model involving the fractions of the predator which are susceptible and those infected and then translate

Mainul Haque

2010-01-01

115

Predation of Notiophilus (Coleoptera: Carabidae) on Collembola as a Predator-Prey Teaching Model.  

ERIC Educational Resources Information Center

|The carabid beetle (Notiophilus) preys readily on an easily-cultured collembolan in simple experimental conditions. Some features of this predator-prey system are outlined to emphasize its use in biology instruction. Experiments with another potential collembolan are described in the context of developing the method for more advanced studies.…

Higgins, R. C.

1982-01-01

116

Cycling of Biogenic Mn-Oxides in a Model Microbial Predator-Prey System  

Microsoft Academic Search

The phase distribution and bioavailability of both essential and toxic trace metals can be profoundly impacted by trophic transfer in microbial food webs. A model microbial predator-prey system was used to elucidate the possible transformations of biogenic manganese oxides as they were consumed by protozoan predators along with their bacterial prey. The ciliated protozoan Tetrahymena thermophila and the Mn-oxidizing bacterium

Carolyn A. Zeiner; Leonard W. Lion; Michael L. Shuler; William C. Ghirose; Anthony Hay

2006-01-01

117

Predator-prey encounter and capture rates for plankton in turbulent environments  

NASA Astrophysics Data System (ADS)

Turbulence plays an important role for predator-prey interactions in aquatic environments. In one sense turbulence benefits the predator by increasing its encounter rate with prey, but on the other hand it can benefit the prey by making them more difficult to catch. In the present study of this problem, a turbulent flow field is obtained by direct numerical solution of the Navier-Stokes equation. The analysis includes the effects of the turbulence on the encounter rate between passively moving predators and prey, and at the same time also models the capture probability depending on the relative turbulent motions of predator and prey. Analytical results for scaling laws for planktonic encounter and capture rates in turbulent environments are obtained in terms of the basic parameters for the problem, and the results are compared with related findings reported in the literature. For large values of the specific energy dissipation rates &z.epsi; the turbulence reduces the capture probability significantly, in part also because the effective capture range reduces for increasing turbulence intensity. The results presented here predict the parameters for an optimum turbulence level for the predator capture rate. For enhanced turbulence levels sudden bursts in the space-time varying velocity field contribute to a noise level that can reduce the probability for capturing prey. We consider cases where the capture range of an organism is comparable to or smaller than the effective Kolmogorov length scale, as well as the opposite limit of larger capture ranges in the inertial range of the turbulence. The reference model assumes spherical interception volumes, but it is demonstrated that the results remain basically valid also for the case where these volumes are hemispherical or conical: the consequences of having a shape of the interception surface deviating from a sphere can be accounted for by an empirical scaling factor, which depends solely on the opening angle of the cone.

Pécseli, H. L.; Trulsen, J.; Fiksen, Ø.

2012-08-01

118

On the relationship between cyclic and hierarchical three-species predator-prey systems and the two-species Lotka-Volterra model  

NASA Astrophysics Data System (ADS)

Stochastic spatial predator-prey competition models represent paradigmatic systems to understand the emergence of biodiversity and the stability of ecosystems. We aim to clarify the relationship and connections between interacting three-species models and the classic two-species Lotka-Volterra (LV) model that entails predator-prey coexistence with long-lived population oscillations. To this end, we utilize mean-field theory and Monte Carlo simulations on two-dimensional square lattices to explore the temporal evolution characteristics of two different interacting three-species predator-prey systems, namely: (1) a cyclic rock-paper-scissors (RPS) model with conserved total particle number but strongly asymmetric reaction rates that lets the system evolve towards one "corner" of configuration space; (2) a hierarchical "food chain" where an additional intermediate species is inserted between the predator and prey in the LV model. For the asymmetric cyclic model variant (1), we demonstrate that the evolutionary properties of both minority species in the (quasi-)steady state of this stochastic spatial three-species "corner" RPS model are well approximated by the two-species LV system, with its emerging characteristic features of localized population clustering, persistent oscillatory dynamics, correlated spatio-temporal patterns, and fitness enhancement through quenched spatial disorder in the predation rates. In contrast, we could not identify any regime where the hierarchical three-species model (2) would reduce to the two-species LV system. In the presence of pair exchange processes, the system remains essentially well-mixed, and we generally find the Monte Carlo simulation results for the spatially extended hierarchical model (2) to be consistent with the predictions from the corresponding mean-field rate equations. If spreading occurs only through nearest-neighbor hopping, small population clusters emerge; yet the requirement of an intermediate species cluster obviously disrupts spatio-temporal correlations between predator and prey, and correspondingly eliminates many of the intriguing fluctuation phenomena that characterize the stochastic spatial LV system.

He, Q.; Täuber, U. C.; Zia, R. K. P.

2012-04-01

119

Intermediate fragmentation per se provides stable predator-prey metapopulation dynamics.  

PubMed

The extent to which a landscape is fragmented affects persistence of predator-prey dynamics. Increasing fragmentation concomitantly imposes conditions that stabilise and destabilise metapopulations. For the first time, we explicitly assessed the hypothesis that intermediate levels provide optimal conditions for stability. We examine four structural changes arising from increased fragmentation: increased fragment number; decreased fragment size; increased connectedness (corridors scaled to fragment); increased fragment heterogeneity (based on connectedness). Using the model predator-prey system (Didinium-Paramecium) we support our hypothesis, by examining replicated metapopulations dynamics at five fragmentation levels. Although both species became extinct without fragmentation, prey survived at low and high levels, and both survived at intermediate levels. By examining time to extinction, maximum abundances, and population asynchrony we conclude that fragmentation produces structural heterogeneity (independent of environmental heterogeneity), which influences stability. Our analysis suggests why some theoretical, field and microcosm studies present conflicting views of fragmentation effects on population persistence. PMID:22639876

Cooper, Jennifer K; Li, Jiqiu; Montagnes, David J S

2012-05-29

120

The dynamical behaviors of a Lotka–Volterra predator–prey model concerning integrated pest management  

Microsoft Academic Search

According to the fact integrated pest management, a Lotka–Volterra predator-prey model with impulsive effect at fixed moment is proposed and investigated. We analyze such system from two cases: general case (taking IPM strategy) and special case (only choosing pesticides). In the first case, we show that there exists a globally asymptotically stable pest-eradication periodic solution when the period of impulsive

Bing Liu; Yujuan Zhang; Lansun Chen

2005-01-01

121

Climate change and cyclic predator-prey population dynamics in the high Arctic  

Microsoft Academic Search

The high Arctic has the world's simplest terrestrial vertebrate predator-prey community, with the collared lemming being the single main prey of four predators, the snowy owl, the Arctic fox, the long-tailed skua, and the stoat. Using a 20-year-long time series of population densities for the five species and a dynamic model that has been previously parameterized for northeast Greenland, we

OLIVIER G ILG; ILKKA H ANSKI

2009-01-01

122

Agent Strategy Generation by Rule Induction in Predator-Prey Problem  

Microsoft Academic Search

This paper contains a proposal of application of rule induction for generating agent strategy. This method of learning is\\u000a tested on a predator-prey domain, in which predator agents learn how to capture preys. We assume that proposed learning mechanism\\u000a will be beneficial in all domains, in which agents can determine direct results of their actions. Experimental results show\\u000a that the

Bart?omiej ?nie?y?ski

123

Talking Helps: Evolving Communicating Agents for the Predator-Prey Pursuit Problem  

Microsoft Academic Search

We analyze a general model of multi-agent communication in which all agents communicate simultaneously to a message board. A genetic algorithm is used to evolve multi-agent languages for the predator agents in a version of the predator-prey pursuit problem. We show that the resulting behavior of the communicating multi-agent system is equivalent to that of a Mealy finite state machine

Kam-Chuen Jim; C. Lee Giles

2001-01-01

124

Talking helps: Evolving communicating agents for the predator-prey pursuit problem  

Microsoft Academic Search

We analyze a general model of multi-agent communication in which all agents communicate simultaneously to a message board. A genetic algorithm is used to evolve multi-agent languages for the predator agents in a version of the predator-prey pursuit problem. We show that the resulting behavior of the communicating multi-agent system is equivalent to that of a Mealy finite state machine

Kam-chuen Jim; C. Lee Giles

2000-01-01

125

Predator-prey relationships of winter flounder, Pleuronectes americanus, in the New York Bight apex  

Microsoft Academic Search

A 39-month study of the effects of cessation of sew­ age sludge disposal inthe New York Bight apex on the diets of certain fishes and on the benthic macro­ faunal community provided an op­ portunity to examine predator-prey relationships of winter flounder, Pleuronectesamericanus,one ofthe common predators in the area. Benthic macrofauna and winter flounder were collected monthly and bimonthly, respectively,

Frank W. Steimle; Dorothy Jeffress; Stephen A. Fromm; Robert N. Reid; Joseph J. Vitaliano; Ann Frame

126

Global boundedness of cyclic predator-prey systems with self-limiting terms  

Microsoft Academic Search

We are concerned with the cyclic predator-prey systems of Volterra-Lotka type where the 1st species feeds on the 2nd, the\\u000a 2nd on the 3rd, …, then-th on the 1st cyclically and each species has the self-limiting terms. The purpose of this paper is to give a necessary and\\u000a sufficient condition for the parameters of this type of systems so that

Yorimasa Oshime

1988-01-01

127

Self-organised spatial patterns and chaos in a ratio-dependent predator–prey system  

Microsoft Academic Search

Mechanisms and scenarios of pattern formation in predator–prey systems have been a focus of many studies recently as they\\u000a are thought to mimic the processes of ecological patterning in real-world ecosystems. Considerable work has been done with\\u000a regards to both Turing and non-Turing patterns where the latter often appears to be chaotic. In particular, spatiotemporal\\u000a chaos remains a controversial issue

Malay Banerjee; Sergei Petrovskii

2011-01-01

128

Uniform persistence and periodic solutions for a discrete predator-prey system with delays  

NASA Astrophysics Data System (ADS)

In this paper, we deal with a discrete predator-prey system with delay. We first give a sufficient condition for the uniform persistence of the system. Assuming that the coefficients in the system are periodic, by generalizing the Yoshizawa's theorem on the existence of periodic solution for ordinary differential equations to the difference equations with delays, we obtain the existence of a periodic solution basing on the uniform persistence result.

Yang, Xitao

2006-04-01

129

Equilibrium points, stability and numerical solutions of fractional-order predator-prey and rabies models  

NASA Astrophysics Data System (ADS)

In this paper we are concerned with the fractional-order predator-prey model and the fractional-order rabies model. Existence and uniqueness of solutions are proved. The stability of equilibrium points are studied. Numerical solutions of these models are given. An example is given where the equilibrium point is a centre for the integer order system but locally asymptotically stable for its fractional-order counterpart.

Ahmed, E.; El-Sayed, A. M. A.; El-Saka, H. A. A.

2007-01-01

130

The dynamics of an impulsive delay predator-prey model with variable coefficients  

Microsoft Academic Search

In this paper, we formulate a new robust two-species nonautonomous predator–prey model with multi-delays and impulsive effects and perform a systematic mathematical and ecological study. Our results in this paper indicate that under the appropriate linear periodic impulsive perturbations, the system is permanent and has a unique positive globally attractive semi-trivial periodic solution. By using the Brouwer fixed point theorem,

Xin-zhu Meng; Lan-sun Chen; Qing-xue Li

2008-01-01

131

Nature-Inspired Congestion Control: Using a Realistic Predator-Prey Model  

Microsoft Academic Search

Nature has been a continuous source of inspiration for many successful techniques, algorithms and computational metaphors.\\u000a We outline such a inspiration here, in the context of bio-inspired congestion control (BICC) algorithms. In this paper a realistic\\u000a predator-prey model is mapped to the Internet congestion control mechanism. This mapping leads to a bio-inspired congestion\\u000a control scheme. Dynamic and equilibrium properties of

Morteza Analoui; Shahram Jamali

2007-01-01

132

Quenching behaviour for a singular predator-prey model  

NASA Astrophysics Data System (ADS)

In this paper, we study the quenching behaviour for a system of two reaction-diffusion equations arising in the modelling of the spatio-temporal interaction of prey and predator populations in fragile environment. We first provide some sufficient conditions on the initial data to have finite time quenching. Then we classify the initial data to distinguish type I quenching and type II quenching, by introducing a delicate energy functional along with the help of some a priori estimates. Finally, we present some results on the quenching set. It can be a singleton, the whole domain, or a compact subset of the domain.

Ducrot, Arnaud; Guo, Jong-Shenq

2012-07-01

133

The influence of predator--prey population dynamics on the long-term evolution of food web structure.  

PubMed

We develop a set of equations to describe the population dynamics of many interacting species in food webs. Predator-prey interactions are nonlinear, and are based on ratio-dependent functional responses. The equations account for competition for resources between members of the same species, and between members of different species. Predators divide their total hunting/foraging effort between the available prey species according to an evolutionarily stable strategy (ESS). The ESS foraging behaviour does not correspond to the predictions of optimal foraging theory. We use the population dynamics equations in simulations of the Webworld model of evolving ecosystems. New species are added to an existing food web due to speciation events, whilst species become extinct due to coevolution and competition. We study the dynamics of species-diversity in Webworld on a macro-evolutionary time-scale. Coevolutionary interactions are strong enough to cause continuous overturn of species, in contrast to our previous Webworld simulations with simpler population dynamics. Although there are significant fluctuations in species diversity because of speciation and extinction, very large-scale extinction avalanches appear to be absent from the dynamics, and we find no evidence for self-organized criticality. PMID:11162055

Drossel, B; Higgs, P G; McKane, A J

2001-01-01

134

Dynamic complexities of predator-prey system in a pulsed chemostat  

NASA Astrophysics Data System (ADS)

In this paper, we study a food chain model with Holling III and Monod type functional response under periodic pulsed conditions, which contains with predator, prey and periodically pulsed substrate. We investigate the subsystem with substrate and prey and study the stability of the boundary periodic solution. By use of standard techniques of bifurcation theory, we prove that above this threshold there are periodic oscillations in prey and predator. Furthermore, by comparing bifurcation diagrams with different bifurcation parameters, we can see that the system shows two kinds of bifurcations, whose are period-doubling and period-halving.

Jia, Jianwen; Zhang, Honghong

2012-06-01

135

Realistic threshold policy with hysteresis to control predator-prey continuous dynamics.  

PubMed

This paper introduces a threshold policy with hysteresis (TPH) for the control of one-predator one-prey models. The models studied are the Lotka-Volterra and Rosenzweig-MacArthur two species density-dependent predator-prey models and the Arditi-Ginzburg nondimensional ratio-dependent model. The proposed policy (TPH) changes the dynamics of the system in such a way that a bounded oscillation is achieved confined to a region that does not allow extinction of either species. The policy can be designed by a suitable choice of so called virtual equilibrium points in a simple and intuitive manner. PMID:19290561

Mendoza Meza, Magno Enrique; Bhaya, Amit

2009-03-17

136

Stabilization of unstable steady states of a continuous stirred tank bioreactor with predator-prey kinetics.  

PubMed

Nonlinear properties of a bioreactor with a developed microbiological predator-prey food chain are discussed. The presence of the predator microorganism completely changes the position and stability of the stationary states. A wide range of unstable steady states appears, associated with high amplitude oscillations of the state variables. Without automatic control such a system can only operate in transient states, with the yield undergoing periodic changes following the dynamics of the stable limit cycle. Technologically, this is undesirable. It has been shown that the oscillations can be removed by employing continuous P or PI controllers. Moreover, with a PI-controller, the predator can be eliminated from the system. PMID:23692816

Tabi?, Boles?aw; Skoneczny, Szymon

2013-05-18

137

Bifurcation analysis for a three-species predator-prey system with two delays  

NASA Astrophysics Data System (ADS)

In this paper, a three-species predator-prey system with two delays is investigated. By choosing the sum ? of two delays as a bifurcation parameter, we first show that Hopf bifurcation at the positive equilibrium of the system can occur as ? crosses some critical values. Second, we obtain the formulae determining the direction of the Hopf bifurcations and the stability of the bifurcating periodic solutions by using the normal form theory and center manifold theorem. Finally, numerical simulations supporting our theoretical results are also included.

Liao, Maoxin; Tang, Xianhua; Xu, Changjin

2012-01-01

138

Traveling Wave Solutions for a Predator-Prey System With Sigmoidal Response Function  

NASA Astrophysics Data System (ADS)

We study the existence of traveling wave solutions for a diffusive predator-prey system. The system considered in this paper is governed by a Sigmoidal response function which is more general than those studied previously. Our method is an improvement to the original method introduced in the work of Dunbar \\cite{Dunbar1,Dunbar2}. A bounded Wazewski set is used in this work while unbounded Wazewski sets were used in \\cite{Dunbar1,Dunbar2}. The existence of traveling wave solutions connecting two equilibria is established by using the original Wazewski's theorem which is much simpler than the extended version in Dunbar's work.

Lin, Xiaobiao; Weng, Peixuan; Wu, Chufen

2011-12-01

139

Hopf bifurcation and center stability for a predator-prey biological economic model with prey harvesting  

NASA Astrophysics Data System (ADS)

In this paper, we investigate Hopf bifurcation and center stability of a predator-prey biological economic model. By employing the local parameterization method, Hopf bifurcation theory and the formal series method, we obtain some testable results on these issues. The economic profit is chosen as a positive bifurcation parameter here. It shows that a phenomenon of Hopf bifurcation occurs as the economic profit increases beyond a certain threshold. Besides, we also find that the center of the biological economic model is always unstable. Finally, some numerical simulations are given to illustrate the effectiveness of our results.

Liu, Wei; Fu, Chaojin; Chen, Boshan

2012-10-01

140

Dynamics of an impulsively controlled Michaelis-Menten type predator-prey system  

NASA Astrophysics Data System (ADS)

We study a predator-prey system with a Michaelis-Menten functional response and impulsive perturbations which contain chemical and biological control terms. By applying the Floquet theory, we establish conditions for the existence and stability of prey-free solutions of the system. We also show the existence of a positive periodic solution of the system by using the bifurcation theorem and find a sufficient condition that makes the system permanent. Moreover, numerical results on impulsive perturbations show that the system we consider can give birth to various kinds of dynamical behaviors.

Baek, Hunki; Lim, Yongdo

2011-04-01

141

Spatial dynamics in a predator-prey model with Beddington-DeAngelis functional response  

NASA Astrophysics Data System (ADS)

In this paper spatial dynamics of the Beddington-DeAngelis predator-prey model is investigated. We analyze the linear stability and obtain the condition of Turing instability of this model. Moreover, we deduce the amplitude equations and determine the stability of different patterns. In Turing space, we found that this model has coexistence of H0 hexagon patterns and stripe patterns, H? hexagon patterns, and H0 hexagon patterns. To better describe the real ecosystem, we consider the ecosystem as an open system and take the environmental noise into account. It is found that noise can decrease the number of the patterns and make the patterns more regular. What is more, noise can induce two kinds of typical pattern transitions. One is from the H? hexagon patterns to the regular stripe patterns, and the other is from the coexistence of H0 hexagon patterns and stripe patterns to the regular stripe patterns. The obtained results enrich the finding in the Beddington-DeAngelis predator-prey model well.

Zhang, Xiao-Chong; Sun, Gui-Quan; Jin, Zhen

2012-02-01

142

Zoogeography and the predator-prey ‘arms race:’ A comparison of eriphia and nerita species from three faunal regions  

Microsoft Academic Search

We measured maximum shell diameters and thicknesses of Nerita funiculata Menke and N. scabricosta Lamarck (Gastropoda: Neritidae), and claw sizes and carapace widths of the predatory crab Eriphia squamata Stimpson (Brachyura: Xanthidae), from the Gulf of California (Eastern Pacific). We also tested the ability of E. squamata to crush Nerita shells of various sizes. We compared this data on predator-prey

William W. Reynolds; Linda J. Reynolds

1977-01-01

143

Predator-Prey Oscillations During Slow L-H Transitions on DIII-D  

NASA Astrophysics Data System (ADS)

A DIII-D operating regime which gives rise to an intermediate phase of experimentally-variable length between the L- and H-modes has been explored. There is no evidence that the plasma is ``dithering" between the L- and H-modes. The intermediate phase is characterized by 1-2 kHz oscillations of the D_? light which are terminated only when the neutral injection power is raised sufficiently. Predator-prey type(J.-N. Leboeuf, et al., Phys. Fluids B 5), 2959 (1993). equations, based on a general drift-wave turbulence model, are found to describe frequency and amplitude characteristics of the oscillations. Outer plasma edge studies showed that the oscillations are caused by periodic instability bursts located inside the separatrix. Fast data taken during these bursts have been obtained from a variety of diagnostics, and provide an extremely detailed picture of the bursts.

Colchin, R. J.; Carreras, B. A.; Maingi, R.; Schaffer, M. J.; Carlstrom, T. N.; Brooks, N. H.; Greenfield, C. M.; McKee, G. R.; Rudakov, D. L.; Rhodes, T. L.; Doyle, E. J.; Austin, M. E.

2001-10-01

144

Analysis of a predator-prey model with Holling II functional response concerning impulsive control strategy  

NASA Astrophysics Data System (ADS)

According to biological and chemical control strategy for pest control, we investigate the dynamic behavior of a Holling II functional response predator-prey system concerning impulsive control strategy-periodic releasing natural enemies and spraying pesticide at different fixed times. By using Floquet theorem and small amplitude perturbation method, we prove that there exists a stable pest-eradication periodic solution when the impulsive period is less than some critical value. Further, the condition for the permanence of the system is also given. Numerical results show that the system we consider can take on various kinds of periodic fluctuations and several types of attractor coexistence and is dominated by periodic, quasiperiodic and chaotic solutions, which implies that the presence of pulses makes the dynamic behavior more complex. Finally, we conclude that our impulsive control strategy is more effective than the classical one if we take chemical control efficiently.

Liu, Bing; Teng, Zhidong; Chen, Lansun

2006-08-01

145

The roles of predator maturation delay and functional response in determining the periodicity of predator-prey cycles.  

PubMed

Population cycles in small mammals have attracted the attention of several generations of theoretical and experimental biologists and continue to generate controversy. Top-down and bottom-up trophic regulations are two recent competing hypotheses. The principal purpose of this paper is to explore the relative contributions of a variety of ecological factors to predator-prey population cycles. Here we suggest that for some species - collared lemmings, snowshoe hares and moose in particular - maturation delay of predators and the functional response of predation appear to be the primary determinants. Our study suggests that maturation delay alone almost completely determines the cycle period, whereas the functional response greatly affects its amplitude and even its existence. These results are obtained from sensitivity analysis of all parameters in a mathematical model of the lemming-stoat delayed system, which is an extension of Gilg's model. Our result may also explain why lemmings have a 4-year cycle whereas snowshoe hares have a 10-year cycle. Our parameterized model supports and extends May's assertion that time delay impacts cycle period and amplitude. Furthermore, if maturation periods of predators are too short or too long, or the functional response resembles Holling Type I, then population cycles do not appear; however, suitable intermediate predator maturation periods and suitable functional responses can generate population cycles for both prey and predators. These results seem to explain why some populations are cyclic whereas others are not. Finally, we find parameterizations of our model that generate a 38-year population cycle consistent with the putative cycles of the moose-wolf interactions on Isle Royale, Michigan. PMID:19563815

Wang, Hao; Nagy, John D; Gilg, Olivier; Kuang, Yang

2009-06-27

146

A Comparison of the Seasonal Movements of Tiger Sharks and Green Turtles Provides Insight into Their Predator-Prey Relationship  

PubMed Central

During the reproductive season, sea turtles use a restricted area in the vicinity of their nesting beaches, making them vulnerable to predation. At Raine Island (Australia), the highest density green turtle Chelonia mydas rookery in the world, tiger sharks Galeocerdo cuvier have been observed to feed on green turtles, and it has been suggested that they may specialise on such air-breathing prey. However there is little information with which to examine this hypothesis. We compared the spatial and temporal components of movement behaviour of these two potentially interacting species in order to provide insight into the predator-prey relationship. Specifically, we tested the hypothesis that tiger shark movements are more concentrated at Raine Island during the green turtle nesting season than outside the turtle nesting season when turtles are not concentrated at Raine Island. Turtles showed area-restricted search behaviour around Raine Island for ?3–4 months during the nesting period (November–February). This was followed by direct movement (transit) to putative foraging grounds mostly in the Torres Straight where they switched to area-restricted search mode again, and remained resident for the remainder of the deployment (53–304 days). In contrast, tiger sharks displayed high spatial and temporal variation in movement behaviour which was not closely linked to the movement behaviour of green turtles or recognised turtle foraging grounds. On average, tiger sharks were concentrated around Raine Island throughout the year. While information on diet is required to determine whether tiger sharks are turtle specialists our results support the hypothesis that they target this predictable and plentiful prey during turtle nesting season, but they might not focus on this less predictable food source outside the nesting season.

Fitzpatrick, Richard; Thums, Michele; Bell, Ian; Meekan, Mark G.; Stevens, John D.; Barnett, Adam

2012-01-01

147

Multiple positive almost periodic solutions to an impulsive non-autonomous Lotka-Volterra predator-prey system with harvesting terms  

NASA Astrophysics Data System (ADS)

We study an impulsive Lotka-Volterra predator-prey system with harvesting terms.Multiplicity of positive almost periodic solutions to the model is obtained.Our methods can be used to study other types of population models.

Li, Yongkun; Ye, Yuan

2013-11-01

148

A study of predator–prey models with the Beddington–DeAnglis functional response and impulsive effect  

Microsoft Academic Search

In this paper, the predator–prey system with the Beddington–DeAngelis functional response is developed, by introducing a proportional periodic impulsive catching or poisoning for the prey populations and a constant periodic releasing for the predator. The Beddington–DeAngelis functional response is similar to the Holling type II functional response but contains an extra term describing mutual interference by predators. This model has

Shuwen Zhang; Lansun Chen

2006-01-01

149

Boundedness of three-species cyclic predator-prey systems which lack some self-limiting terms  

Microsoft Academic Search

We consider the three species cyclic predator-prey systems of Lotka-Volterra type where the first species feeds on the second,\\u000a the second on the third, the third on the first, cyclically. Each of the self-limiting terms may be either present or absent.\\u000a However, we impose the condition that each species remains bounded in the absence of the other two. Under these

Yorimasa Oshime

1993-01-01

150

A predator-prey model with diseases in both prey and predator  

NASA Astrophysics Data System (ADS)

In this paper, we present and analyze a predator-prey model, in which both predator and prey can be infected. Each of the predator and prey is divided into two categories, susceptible and infected. The epidemics cannot be transmitted between prey and predator by predation. The predation ability of susceptible predators is stronger than infected ones. Likewise, it is more difficult to catch a susceptible prey than an infected one. And the diseases cannot be hereditary in both of the predator and prey populations. Based on the assumptions above, we find that there are six equilibrium points in this model. Using the base reproduction number, we discuss the stability of the equilibrium points qualitatively. Then both of the local and global stabilities of the equilibrium points are analyzed quantitatively by mathematical methods. We provide numerical results to discuss some interesting biological cases that our model exhibits. Lastly, we discuss how the infectious rates affect the stability, and how the other parameters work in the five possible cases within this model.

Gao, Xubin; Pan, Qiuhui; He, Mingfeng; Kang, Yibin

2013-12-01

151

Stable oscillations of a predator prey probabilistic cellular automaton: a mean-field approach  

NASA Astrophysics Data System (ADS)

We analyze a probabilistic cellular automaton describing the dynamics of coexistence of a predator-prey system. The individuals of each species are localized over the sites of a lattice and the local stochastic updating rules are inspired by the processes of the Lotka-Volterra model. Two levels of mean-field approximations are set up. The simple approximation is equivalent to an extended patch model, a simple metapopulation model with patches colonized by prey, patches colonized by predators and empty patches. This approximation is capable of describing the limited available space for species occupancy. The pair approximation is moreover able to describe two types of coexistence of prey and predators: one where population densities are constant in time and another displaying self-sustained time oscillations of the population densities. The oscillations are associated with limit cycles and arise through a Hopf bifurcation. They are stable against changes in the initial conditions and, in this sense, they differ from the Lotka-Volterra cycles which depend on initial conditions. In this respect, the present model is biologically more realistic than the Lotka-Volterra model.

Tomé, Tânia; de Carvalho, Kelly C.

2007-10-01

152

Biomagnification and polychlorinated biphenyl congener distribution in an aquatic predator-prey, host-parasite system.  

PubMed

Biomagnification and polychlorinated biphenyl (PCB) congener distribution was examined in a predator-prey, host-parasite system, in which Atlantic salmon (Salmo salar) preyed upon sprat (Sprattus sprattus). Eubothrium crassum was an intestinal parasite in salmon that also "preyed upon" sprat, because the parasites gained access to foodstuffs via the host (salmon) gut. Salmon contained significantly higher concentrations of total PCBs compared to both parasites and prey (sprat), but no difference in PCB concentration was found between sprat and E. crassum. Salmon biomagnified several PCB congeners from their diet (sprat), whereas parasites did not, despite the fact that both salmon and their parasites ingested the same prey. Differences in nutrient uptake mechanisms between the host and their parasites, in addition to the lack of a gastrointestinal tract in the cestode, may explain the lack of biomagnification in E. crassum. No difference was found in PCB congener distribution between parasites, salmon, and sprat, and none of the animal types showed a preference for accumulating more or less lipophilic congeners (congeners with a high or low octanol/water partition coefficient [K(ow)]). Biomagnification factors for individual congeners in salmon did not increase with K(ow); rather, they were constant, as shown by a linear relationship for congener concentration in prey and predator. PMID:17521127

Persson, Maria E; Larsson, Per; Stenroth, Patrik

2007-05-01

153

Phase diagram of a cyclic predator-prey model with neutral-pair exchange  

NASA Astrophysics Data System (ADS)

In this paper we obtain the phase diagram of a four-species predator-prey lattice model by using the proposed gradient method. We consider cyclic transitions between consecutive states, representing invasion or predation, and allowed the exchange between neighboring neutral pairs. By applying a gradient in the invasion rate parameter one can see, in the same simulation, the presence of two symmetric absorbing phases, composed by neutral pairs, and an active phase that includes all four species. In this sense, the study of a single-valued interface and its fluctuations give the critical point of the irreversible phase transition and the corresponding universality classes. Also, the consideration of a multivalued interface and its fluctuations bring the percolation threshold. We show that the model presents two lines of irreversible first-order phase transition between the two absorbing phases and the active phase. Depending on the value of the system parameters, these lines can converge into a triple point, which is the beginning of a first-order irreversible line between the two absorbing phases, or end in two critical points belonging to the directed percolation universality class. Standard simulations for some characteristic values of the parameters confirm the order of the transitions as determined by the gradient method. Besides, below the triple point the model presents two standard percolation lines in the active phase and above a first-order percolation transition as already found in other similar models.

Guisoni, Nara C.; Loscar, Ernesto S.; Girardi, Mauricio

2013-08-01

154

A Bayesian estimation of a stochastic predator-prey model of economic fluctuations  

NASA Astrophysics Data System (ADS)

In this paper, we develop a Bayesian framework for the empirical estimation of the parameters of one of the best known nonlinear models of the business cycle: The Marx-inspired model of a growth cycle introduced by R. M. Goodwin. The model predicts a series of closed cycles representing the dynamics of labor's share and the employment rate in the capitalist economy. The Bayesian framework is used to empirically estimate a modified Goodwin model. The original model is extended in two ways. First, we allow for exogenous periodic variations of the otherwise steady growth rates of the labor force and productivity per worker. Second, we allow for stochastic variations of those parameters. The resultant modified Goodwin model is a stochastic predator-prey model with periodic forcing. The model is then estimated using a newly developed Bayesian estimation method on data sets representing growth cycles in France and Italy during the years 1960-2005. Results show that inference of the parameters of the stochastic Goodwin model can be achieved. The comparison of the dynamics of the Goodwin model with the inferred values of parameters demonstrates quantitative agreement with the growth cycle empirical data.

Dibeh, Ghassan; Luchinsky, Dmitry G.; Luchinskaya, Daria D.; Smelyanskiy, Vadim N.

2007-06-01

155

Plant strategies of manipulating predatorprey interactions through allelochemicals: Prospects for application in pest control  

Microsoft Academic Search

To understand the role of allelochemicals in predator-prey interactions it is not sufficient to study the behavioral responses of predator and prey. One should elucidate the origin of the allelochemicals and be aware that it may be located at another trophic level. These aspects are reviewed for predator-prey interactions in general and illustrated in detail for interactions between predatory mites

Marcel Dicke; Maurice W. Sabelis; Junji Takabayashi; Jan Bruin; Maarten A. Posthumus

1990-01-01

156

Harvesting creates ecological traps: consequences of invisible mortality risks in predator-prey metacommunities.  

PubMed

Models of two-patch predator-prey metacommunities are used to explore how the global predator population changes in response to additional mortality in one of the patches. This could describe the dynamics of a predator in an environment that includes a refuge area where that predator is protected and a spatially distinct ("risky") area where it is harvested. The predator's movement is based on its perceived fitness in the two patches, but the risk from the additional mortality is potentially undetectable; this often occurs when the mortality is from human harvesting or from a novel type of top predator. Increases in undetected mortality in the risky area can produce an abrupt collapse of either the refuge population or of the entire predator population when the mortality rate exceeds a threshold level. This is due to the attraction of the risky patch, which has abundant prey due to its high predator mortality. Extinction of the refuge predator population does not occur when the refuge patch has a higher maximum per capita predator growth rate than the exploited patch because the refuge is then more attractive when the predator is rare. The possibility of abrupt extinction of one or both patches from high densities in response to a small increase in harvest is often associated with alternative states. In such cases, large reductions in mortality may be needed to avoid extinction in a collapsing predator population, or to reestablish an extinct population. Our analysis provides a potential explanation for sudden collapses of harvested populations, and it argues for more consideration of adaptive movement in designing protected areas. PMID:22624310

Abrams, Peter A; Ruokolainen, Lasse; Shuter, Brian J; McCann, Kevin S

2012-02-01

157

Predator-Prey Model for Haloes in Saturn’s Rings  

NASA Astrophysics Data System (ADS)

Particles in Saturn’s rings have a tripartite nature: (1) a broad distribution of fragments from the disruption of a previous moon that accrete into (2) transient aggregates, resembling piles of rubble, covered by a (3) regolith of smaller grains that result from collisions and meteoritic grinding. Evidence for this triple architecture of ring particles comes from a multitude of Cassini observations. In a number of ring locations (including Saturn’s F ring, the shepherded outer edges of rings A and B and at the locations of the strongest density waves) aggregation and dis-aggregation are operating now. ISS, VIMS, UVIS spectroscopy and occultations show haloes around the strongest density waves. Based on a predator-prey model for ring dynamics, we offer the following explanation: 1. Cyclic velocity changes cause the perturbed regions to reach higher collision speeds at some orbital phases, which preferentially removes small regolith particles; 2. This forms a bright halo around the ILR, if the forcing is strong enough; 3. Surrounding particles diffuse back too slowly to erase the effect; they diffuse away to form the halo. The most rapid time scale is for forcing/aggregate growth/disaggregation; then irreversible regolith erosion; diffusion and/or ballistic transport; and slowest, meteoritic pollution/darkening. We observe both smaller and larger particles at perturbed regions. Straw, UVIS power spectral analysis, kittens and equinox objects show the prey (mass aggregates); while the haloes’ VIMS spectral signature, correlation length and excess variance are created by the predators (velocity dispersion) in regions stirred in the rings. Moon forcing triggers aggregation to create longer-lived aggregates that protect their interiors from meteoritic darkening and recycle the ring material to maintain the current purity of the rings. It also provides a mechanism for creation of new moons at resonance locations in the Roche zone, as proposed by Charnoz etal and Canup.

Esposito, Larry W.; Madhusudhanan, P.; Colwell, J. E.; Bradley, E.; Sremcevic, M.

2013-10-01

158

Role of Zonal Flow Predator-Prey Oscillations in Triggering the Transition to H-Mode Confinement  

NASA Astrophysics Data System (ADS)

Direct evidence of zonal flow (ZF) predator-prey oscillations and the synergistic roles of ZF- and equilibrium E×B flow shear in triggering the low- to high-confinement (L- to H-mode) transition in the DIII-D tokamak is presented. Periodic turbulence suppression is first observed in a narrow layer at and just inside the separatrix when the shearing rate transiently exceeds the turbulence decorrelation rate. The final transition to H mode with sustained turbulence and transport reduction is controlled by equilibrium E×B shear due to the increasing ion pressure gradient.

Schmitz, L.; Zeng, L.; Rhodes, T. L.; Hillesheim, J. C.; Doyle, E. J.; Groebner, R. J.; Peebles, W. A.; Burrell, K. H.; Wang, G.

2012-04-01

159

Role of zonal flow predator-prey oscillations in triggering the transition to H-mode confinement.  

PubMed

Direct evidence of zonal flow (ZF) predator-prey oscillations and the synergistic roles of ZF- and equilibrium E×B flow shear in triggering the low- to high-confinement (L- to H-mode) transition in the DIII-D tokamak is presented. Periodic turbulence suppression is first observed in a narrow layer at and just inside the separatrix when the shearing rate transiently exceeds the turbulence decorrelation rate. The final transition to H mode with sustained turbulence and transport reduction is controlled by equilibrium E×B shear due to the increasing ion pressure gradient. PMID:22587261

Schmitz, L; Zeng, L; Rhodes, T L; Hillesheim, J C; Doyle, E J; Groebner, R J; Peebles, W A; Burrell, K H; Wang, G

2012-04-12

160

Existence of periodic solutions for a predator-prey system with sparse effect and functional response on time scales  

NASA Astrophysics Data System (ADS)

In this paper, we systematically investigates the existence of periodic solutions of a predator-prey system with sparse effect and Beddington-DeAngelis or Holling III functional response on time scales. By using a continuation theorem based on coincidence degree theory, we obtain sufficient criteria for the existence of periodic solutions for the systems. Moreover, when the time scale T is chosen as R or Z, the existence of the periodic solutions of the corresponding continuous and discrete models follows. Therefore, the methods are unified to provide the existence of the desired solutions for the continuous differential equations and discrete difference equations.

Tong, Yu; Liu, Zhenjie; Gao, Zhiying; Wang, Yonghong

2012-08-01

161

Diffusion effect and stability analysis of a predator-prey system described by a delayed reaction-diffusion equations  

NASA Astrophysics Data System (ADS)

In this paper, we consider a delayed reaction-diffusion equations which describes a two-species predator-prey system with diffusion terms and stage structure. By using the linearization method and the method of upper and lower solutions, we study the local and global stability of the constant equilibria, respectively. The results show that the free diffusion of the delayed reaction-diffusion equations has no effect on the populations when the diffusion is too slow; otherwise, the free diffusion has a certain influence on the populations, however, the influence can be eliminated by improving the parameters to satisfy some suitable conditions.

Ge, Zhihao; He, Yinnian

2008-03-01

162

A predator-prey model for moon-triggered clumping in Saturn's rings  

NASA Astrophysics Data System (ADS)

UVIS occultation data show clumping in Saturn's F ring and at the B ring outer edge, indicating aggregation and disaggregation at these locations that are perturbed by Prometheus and by Mimas. The inferred timescales range from hours to months. Occultation profiles of the edge show wide variability, indicating perturbations by local mass aggregations. Structure near the B ring edge is seen in power spectral analysis at scales 200-2000 m. Similar structure is also seen at the strongest density waves, with significance increasing with resonance strength. For the B ring outer edge, the strongest structure is seen at longitudes 90° and 270° relative to Mimas. This indicates a direct relation between the moon and the ring clumping. We propose that the collective behavior of the ring particles resembles a predator-prey system: the mean aggregate size is the prey, which feeds the velocity dispersion; conversely, increasing dispersion breaks up the aggregates. Moons may trigger clumping by streamline crowding, which reduces the relative velocity, leading to more aggregation and more clumping. Disaggregation may follow from disruptive collisions or tidal shedding as the clumps stir the relative velocity. For realistic values of the parameters this yields a limit cycle behavior, as for the ecology of foxes and hares or the "boom-bust" economic cycle. Solving for the long-term behavior of this forced system gives a periodic response at the perturbing frequency, with a phase lag roughly consistent with the UVIS occultation measurements. We conclude that the agitation by the moons in the F ring and at the B ring outer edge drives aggregation and disaggregation in the forcing frame. This agitation of the ring material may also allow fortuitous formation of solid objects from the temporary clumps, via stochastic processes like compaction, adhesion, sintering or reorganization that drives the denser parts of the aggregate to the center or ejects the lighter elements. Any of these more persistent objects would then orbit at the Kepler rate. We would also expect the formation of clumps and some more permanent objects at the other perturbed regions in the rings… including satellite resonances, shepherded ring edges, and near embedded objects like Pan and Daphnis (where the aggregation/disaggregation cycles are forced similar to Prometheus forcing of the F ring).

Esposito, Larry W.; Albers, Nicole; Meinke, Bonnie K.; Srem?evi?, Miodrag; Madhusudhanan, Prasanna; Colwell, Joshua E.; Jerousek, Richard G.

2012-01-01

163

Prey evolution on the time scale of predator-prey dynamics revealed by allele-specific quantitative PCR  

PubMed Central

Using rotifer–algal microcosms, we tracked rapid evolution resulting from temporally changing natural selection in ecological predator–prey dynamics. We previously demonstrated that predator–prey oscillations in rotifer–algal laboratory microcosms are qualitatively altered by the presence of genetic variation within the prey. In that study, changes in algal gene frequencies were inferred from their effects on population dynamics but not observed directly. Here, we document rapid prey evolution in this system by directly observing changes in Chlorella vulgaris genotype frequencies as the abundances of these algae and their consumer, Brachionus calyciflorus, change through time. We isolated a group of algal clones that we could distinguish by using microsatellite-DNA markers, and developed an allele-specific quantitative PCR technique (AsQ-PCR) to quantify the frequencies of pairs of clones in mixed culture. We showed that two of these genotypes exhibited a fitness tradeoff in which one was more resistant to predation (more digestion-resistant), and the other had faster population growth under limiting nitrogen concentrations. A fully specified mathematical model for the rotifer–algal population and evolutionary dynamics predicted that these two clones would undergo a single oscillation in clonal frequencies followed by asymptotic fixation of the more resistant clone, rather than the recurrent oscillations previously observed with other algal clones. We used AsQ-PCR to confirm this prediction: the superior competitor dominated initially, but as rotifer densities increased, the more predator-resistant clone predominated.

Meyer, Justin R.; Ellner, Stephen P.; Hairston, Nelson G.; Jones, Laura E.; Yoshida, Takehito

2006-01-01

164

Generation Time Ratios—Determinants of Prey Abundance in Insect Predator–Prey Interactions  

Microsoft Academic Search

The potential fitness of an adult insect predator depends mainly on the future trends in resource availability throughout the period of development of its larvae, because they, unlike the adult, are confined to a patch. Thus, adult oviposition strategy is likely to be determined by the bottlenecks in resources that occur during the period of its offsprings' development. Therefore, the

Pavel Kindlmann; Anthony F. G. Dixon

1999-01-01

165

Modelling of predator-prey trophic interactions. Part I: two trophic levels.  

PubMed

A class of lumped parameter models to describe the local dynamics in a controlled environment of a two-trophic chain is considered. The class is characterized by a trophic function (functional response of predator to the abundance of prey) depending on the ratio of prey biomass x and a linear function of predator biomass y: f(qx/[(1-rho)k + rhoy]), where q is the efficiency of the predation process, k is a reference biomass, and rho (0 < or = rho < or = 1) specifies the predation model. The trophic function is defined only by some properties determining its shape. A stability analysis of the models has been performed by taking the parameters q and rho as bifurcation parameters: the regions in the (rho,q) plane of existence and stability of nonnegative equilibrium states and limit cycles are determined. This analysis shows that the behaviour of the models is qualitatively similar for 0 < or = rho < 1 (in particular the null state is always a saddle point), while the value rho=1 gives rise to some kind of structural instability of the system (in particular the null state becomes an attractor for sufficiently high predation efficiency). PMID:15772823

Buffoni, G; Cassinari, M P; Groppi, M; Serluca, M

2005-03-15

166

Influences of Physical and Chemical Alterations on Predator-Prey Interactions.  

National Technical Information Service (NTIS)

These field studies have shown that impingement of fish at one steam plant is similar in three respects to predation of those fish by a natural predator. The similarities are (1) numbers of threadfin killed over time, (2) proportion of species killed, and...

C. C. Coutant R. B. McLean D. L. DeAngelis

1978-01-01

167

Predator-prey interactions in the spinifex grasslands of central Australia  

Microsoft Academic Search

Predation by exotic predators (cats Felis catus and foxes Vulpes vulpes) is believed to be one of the factors that has contributed to the decline of medium-sized mammals in arid Australia. Other factors include habitat degradation by introduced herbivores (rabbits Oryctolagus cuniculus and grazing stock) and altered fire regimes after Aboriginal people moved into permanent settlements. In general, the impact

Rachel M Paltridge

2005-01-01

168

Predator-prey interactions between the larvacean Oikopleura dioica and bacterioplankton in enclosed water columns  

Microsoft Academic Search

The larvacean Oikopleura dioica Fol was fed 3H-labeled natural assemblages of marine bacterioplankton. Grazing rates ranged from 100 ml day-1 individual-1 and were highly dependent onlarvacean body size. These rates were combined with estimates of abundance of O. dioica in large floating enclosures with semi-natural populations (Controlled Ecosystems Populations Experiment, CEPEX) to determine the impact of the larvacean on the

K. R. King; J. T. Hollibaugh; F. Azam

1980-01-01

169

Attack or attacked: the sensory and fluid mechanical constraints of copepods' predator-prey interactions.  

PubMed

Many animals are predator and prey at the same time. This dual position represents a fundamental dilemma because gathering food often leads to increased exposure to predators. The optimization of the tradeoff between eating and not being eaten depends strongly on the sensing, feeding, and mechanisms for mobility of the parties involved. Here, I describe the mechanisms of sensing, escaping predators, and capturing prey in marine pelagic copepods. I demonstrate that feeding tradeoffs vary with feeding mode, and I describe simple fluid mechanical models that are used to quantify these tradeoffs and review observations and experiments that support the assumptions and test the predictions. I conclude by presenting a mechanistically underpinned model that predicts optimal foraging behaviors and the resulting size-scaling and magnitude of copepods' clearance rates. PMID:23613321

Kiørboe, Thomas

2013-04-23

170

PREDATOR-PREY (VOLE-CRICKET) INTERACTIONS: THE EFFECTS OF WOOD PRESERVATIVES  

EPA Science Inventory

The rate of loss of crickets (Acheta domestica), with and without the presence of an adventitious predator, the gray-tailed vole (Microtus canicaudus), has been studied in Terrestrial Microcosm Chambers (TMC-II) treated with pine stakes impregnated with creosote, bis(tri-n-butylt...

171

Predator-prey interaction between drones of Apis mellifera carnica and insectivorous birds  

Microsoft Academic Search

Large offers of food usually do not remain unexploited in nature. For that reason several mechanisms have evolved to counteract\\u000a predation, such as congregating in masses or producing a repellent substance. We investigated whether drones are preyed upon\\u000a in any specific way by two swallow species, Hirundo rustica or Delichon urbica, in their drone congregation areas. Our results clearly showed

Martin H. Kärcher; Peter H. W. Biedermann; Norbert Hrassnigg; Karl Crailsheim

2008-01-01

172

Predator-Prey Oscillations and Zonal Flow-Induced Turbulence Suppression Preceding the L-H Transition  

NASA Astrophysics Data System (ADS)

Understanding the L- to H-mode transition and the density/rotation dependence of the H-mode power threshold is important for the design and predictive modeling of burning plasma experiments. We present here direct experimental evidence of the importance of predator-prey oscillations and turbulence/transport regulation by low frequency zonal flows (ZFs) at the L-H transition. Near the H-mode power threshold, a narrow oscillating flow layer develops at/inside the separatrix in a neutral beam-heated DIII-D plasma. Toroidal and radial correlation of the ExB velocity, as measured by Doppler backscattering (DBS), increase at the transition to this ``dithering'' state. The observed oscillation is consistent with a radially propagating ZF with a frequency much below the expected local GAM frequency. Periodic turbulence suppression due to ZF shearing is first observed when the turbulence decorrelation rate decreases sharply (within 0.1,ms) at the transition to the dithering state and the increasing ZF shearing rate locally surpasses the decorrelation rate. The flow layer then expands radially inwards. The ZF amplitude lags the density fluctuation amplitude by 90^o. The ``final" H-mode transition (sustained turbulence/transport reduction) appears linked to increasing equilibrium flow shear due to the increasing ion pressure gradient. Both features are consistent with the predator-prey model of the L-H transition [1]. The transition dynamics is revealed with high time (<1,s) and spatial resolution (<0.5,cm), combining eight channel and five channel DBS systems, separated 180^o toroidally, with fast profile reflectometry. 3pt [1] E.J. Kim and P.H. Diamond, Phys. Rev. Lett. 90, 185006 (2003).

Schmitz, L.

2011-11-01

173

Predicting prey population dynamics from kill rate, predation rate and predator-prey ratios in three wolf-ungulate systems.  

PubMed

1.?Predation rate (PR) and kill rate are both fundamental statistics for understanding predation. However, relatively little is known about how these statistics relate to one another and how they relate to prey population dynamics. We assess these relationships across three systems where wolf-prey dynamics have been observed for 41 years (Isle Royale), 19 years (Banff) and 12 years (Yellowstone). 2.?To provide context for this empirical assessment, we developed theoretical predictions of the relationship between kill rate and PR under a broad range of predator-prey models including predator-dependent, ratio-dependent and Lotka-Volterra dynamics. 3.?The theoretical predictions indicate that kill rate can be related to PR in a variety of diverse ways (e.g. positive, negative, unrelated) that depend on the nature of predator-prey dynamics (e.g. structure of the functional response). These simulations also suggested that the ratio of predator-to-prey is a good predictor of prey growth rate. That result motivated us to assess the empirical relationship between the ratio and prey growth rate for each of the three study sites. 4.?The empirical relationships indicate that PR is not well predicted by kill rate, but is better predicted by the ratio of predator-to-prey. Kill rate is also a poor predictor of prey growth rate. However, PR and ratio of predator-to-prey each explained significant portions of variation in prey growth rate for two of the three study sites. 5.?Our analyses offer two general insights. First, Isle Royale, Banff and Yellowstone are similar insomuch as they all include wolves preying on large ungulates. However, they also differ in species diversity of predator and prey communities, exploitation by humans and the role of dispersal. Even with the benefit of our analysis, it remains difficult to judge whether to be more impressed by the similarities or differences. This difficulty nicely illustrates a fundamental property of ecological communities. Second, kill rate is the primary statistic for many traditional models of predation. However, our work suggests that kill rate and PR are similarly important for understanding why predation is such a complex process. PMID:21569029

Vucetich, John A; Hebblewhite, Mark; Smith, Douglas W; Peterson, Rolf O

2011-05-13

174

Fitting a predator prey model to zooplankton time-series data in the Gironde estuary (France): Ecological significance of the parameters  

NASA Astrophysics Data System (ADS)

The relationships between the seasonal fluctuations of the copepod Eurytemora affinis and the mysid Neomysis integer were studied from observed data and experimental results, using a predator prey model in the oligo-mesohaline area of the Gironde estuary. Mean seasonal fluctuations of abundances were derived from long term data series collected from 1978 to 2003 for both species. In situ predator prey experiments over a seasonal cycle were used to estimate the seasonal variation of the consumption rate of N. integer on E. affinis and to verify the order of magnitude of the biological parameters given by the model. Predator prey experiments revealed a high seasonal variation in maximum consumption rates with a mean of 56 ± 9 ind. pred-1 d-1. Maximum consumption rates were always higher for adults than for juveniles of Neomysis integer. Recorded selectivities were higher on nauplii than on copepodids + adults of Eurytemora affinis, both for the juveniles and the adults of N. integer. Neomysis integer mainly fed on meroplanktonic larvae, when they were available in higher abundances, than E. affinis in their environment. Spring increases of abundance for Eurytemora affinis copepodids + adults seemed to be mainly controlled by temperature whereas its decreasing abundance in summer was more related to Neomysis integer predation, suggesting that summer fluctuations of E. affinis abundance are probably controlled by mysid predation at summer times. Using a Lotka Volterra predator prey model, the seasonal peak of abundance of the mysid N. integer was well reproduced considering a predation on copepodids + adults of E. affinis, and suggested a dependence between mysid and copepod seasonal variations. However, the seasonal peak amplitude could not be explained solely by a predation on copepodids + adults or on nauplii of the copepod. Thus, N. integer is probably dependent on the seasonal fluctuations of the copepod's abundance, complementing its diet with macrophytal detritus during periods of scarce food.

David, Valérie; Chardy, Pierre; Sautour, Benoît

2006-05-01

175

An individual-based evolving predator-prey ecosystem simulation using a fuzzy cognitive map as the behavior model.  

PubMed

We present an individual-based predator-prey model with, for the first time, each agent behavior being modeled by a fuzzy cognitive map (FCM), allowing the evolution of the agent behavior through the epochs of the simulation. The FCM enables the agent to evaluate its environment (e.g., distance to predator or prey, distance to potential breeding partner, distance to food, energy level) and its internal states (e.g., fear, hunger, curiosity), and to choose several possible actions such as evasion, eating, or breeding. The FCM of each individual is unique and is the result of the evolutionary process. The notion of species is also implemented in such a way that species emerge from the evolving population of agents. To our knowledge, our system is the only one that allows the modeling of links between behavior patterns and speciation. The simulation produces a lot of data, including number of individuals, level of energy by individual, choice of action, age of the individuals, and average FCM associated with each species. This study investigates patterns of macroevolutionary processes, such as the emergence of species in a simulated ecosystem, and proposes a general framework for the study of specific ecological problems such as invasive species and species diversity patterns. We present promising results showing coherent behaviors of the whole simulation with the emergence of strong correlation patterns also observed in existing ecosystems. PMID:19463060

Gras, Robin; Devaurs, Didier; Wozniak, Adrianna; Aspinall, Adam

2009-01-01

176

A Predator-Prey Model with a Holling Type I Functional Response Including a Predator Mutual Interference  

NASA Astrophysics Data System (ADS)

The most widely used functional response in describing predator-prey relationships is the Holling type II functional response, where per capita predation is a smooth, increasing, and saturating function of prey density. Beddington and DeAngelis modified the Holling type II response to include interference of predators that increases with predator density. Here we introduce a predator-interference term into a Holling type I functional response. We explain the ecological rationale for the response and note that the phase plane configuration of the predator and prey isoclines differs greatly from that of the Beddington-DeAngelis response; for example, in having three possible interior equilibria rather than one. In fact, this new functional response seems to be quite unique. We used analytical and numerical methods to show that the resulting system shows a much richer dynamical behavior than the Beddington-DeAngelis response, or other typically used functional responses. For example, cyclic-fold, saddle-fold, homoclinic saddle connection, and multiple crossing bifurcations can all occur. We then use a smooth approximation to the Holling type I functional response with predator mutual interference to show that these dynamical properties do not result from the lack of smoothness, but rather from subtle differences in the functional responses.

Seo, Gunog; Deangelis, Donald L.

2011-12-01

177

Interaction between host genotype and environmental conditions affects bacterial density in Wolbachia symbiosis.  

PubMed

Regulation of microbial population density is a necessity in stable symbiotic interactions. In Wolbachia symbiosis, both bacterial and host genotypes are involved in density regulation, but environmental factors may also affect bacterial population density. Here, we studied the interaction between three strains of Wolbachia in two divergent homozygous lines of the wasp Leptopilina heterotoma at two different temperatures. Wolbachia density varied between the two host genotypes at only one temperature. Moreover, at this temperature, reciprocal-cross F1 insects displayed identical Wolbachia densities, which were intermediate between the densities in the two parental lines. While these findings confirm that the host genotype plays an important role in Wolbachia density, they also highlight its interaction with environmental conditions, making possible the evolution of local adaptations for the regulation of Wolbachia density. PMID:17251124

Mouton, Laurence; Henri, Hélène; Charif, Delphine; Boulétreau, Michel; Vavre, Fabrice

2007-04-22

178

Managing Excessive Predation in a Predator-Prey Setting: The Case of Piping Plovers  

Microsoft Academic Search

Ecosystems involve interspecies interactions that can be influenced by human interventions. Prior work shows interventions that ignore these interactions cause efficiency-reducing ecosystem externalities. We show inefficiencies may also be attributable to nature, via interspecies interactions generating excessive competition or predation. Ecosystem management therefore may involve correcting both ecological and economic inefficiencies. We explore ecosystem management to correct ecological inefficiencies from

Richard T. Melstrom; Richard D. Horan

2012-01-01

179

Consequences of size structure in the prey for predator–prey dynamics: the composite functional response  

Microsoft Academic Search

Summary 1. Current formulations of functional responses assume that the prey is homogeneous and independent of intraspecific processes. Most prey populations consist of different coexisting size classes that often engage in asymmetrical intraspecific interactions, including cannibalism, which can lead to nonlinear interaction effects. This may be important as the size structure with the prey could alter the overall density-dependent predation

Volker H. W. Rudolf

2008-01-01

180

Predators indirectly control vector- borne disease: linking predator prey and host -pathogen models  

Microsoft Academic Search

Pathogens transmitted by arthropod vectors are common in human populations, agricultural systems and natural communities. Transmission of these vector-borne pathogens depends on the population dynamics of the vector species as well as its interactions with other species within the community. In particular, predation may be sufficient to control pathogen prevalence indirectly via the vector. To examine the indirect effect of

Sean M. Moore; Elizabeth T. Borer; Parviez R. Hosseini

2009-01-01

181

The anatomy of predator–prey dynamics in a changing climate  

Microsoft Academic Search

Summary 1. Humans are increasingly influencing global climate and regional predator assem- blages, yet a mechanistic understanding of how climate and predation interact to affect fluctuations in prey populations is currently lacking. 2. Here we develop a modelling framework to explore the effects of different predation strategies on the response of age-structured prey populations to a changing climate. 3. We

CHRISTOPHER C. WILMERS; ERIC POST; ALAN HASTINGS

2007-01-01

182

Instability of defensive alliances in the predator-prey model on complex networks  

NASA Astrophysics Data System (ADS)

A model of six-species food web is studied in the viewpoint of spatial interaction structures. Each species has two predators and two preys, and it was previously known that the defensive alliances of three cyclically predating species self-organize in two dimensions. The alliance-breaking transition occurs as either the mutation rate is increased or interaction topology is randomized in the scheme of the Watts-Strogatz model. In the former case of temporal disorder, via the finite-size scaling analysis, the transition is clearly shown to belong to the two-dimensional Ising universality class. In contrast, the geometric or spatial randomness for the latter case yields a discontinuous phase transition. The mean-field limit of the model is analytically solved and then compared with numerical results. The dynamic universality and the temporally periodic behaviors are also discussed.

Kim, Beom Jun; Liu, Jianbin; Um, Jaegon; Lee, Sung-Ik

2005-10-01

183

Turing patterns and apparent competition in predator-prey food webs on networks  

NASA Astrophysics Data System (ADS)

Reaction-diffusion systems may lead to the formation of steady-state heterogeneous spatial patterns, known as Turing patterns. Their mathematical formulation is important for the study of pattern formation in general and plays central roles in many fields of biology, such as ecology and morphogenesis. Here we show that Turing patterns may have a decisive role in shaping the abundance distribution of predators and prey living in patchy landscapes. We extend the original model proposed by Nakao and Mikhailov [Nat. Phys.1745-247310.1038/nphys1651 6, 544 (2010)] by considering food chains with several interacting pairs of prey and predators distributed on a scale-free network of patches. We identify patterns of species distribution displaying high degrees of apparent competition driven by Turing instabilities. Our results provide further indication that differences in abundance distribution among patches can be generated dynamically by self organized Turing patterns and not only by intrinsic environmental heterogeneity.

Fernandes, L. D.; de Aguiar, M. A. M.

2012-11-01

184

The limits of adaptation: humans and the predator-prey arms race.  

PubMed

In the history of life, species have adapted to their consumers by evolving a wide variety of defenses. By contrast, animal species harvested in the wild by humans have not adapted structurally. Nonhuman predators have high failure rates at one or more stages of an attack, indicating that victim species have spatial refuges or phenotypic defenses that permit further functional improvement. A new compilation confirms that species in the wild cannot achieve immunity from human predation with structural defenses. The only remaining options are to become undesirable or to live in or escape to places where harvesting by people is curtailed. Escalation between prey defenses and predators' weapons may be restricted under human dominance to interactions involving those low-level predators that have benefited from human overexploitation of top consumers. PMID:22759280

Vermeij, Geerat J

2012-03-03

185

Nonlinearities Lead to Qualitative Differences in Population Dynamics of Predator-Prey Systems  

PubMed Central

Since typically there are many predators feeding on most herbivores in natural communities, understanding multiple predator effects is critical for both community and applied ecology. Experiments of multiple predator effects on prey populations are extremely demanding, as the number of treatments and the amount of labour associated with these experiments increases exponentially with the number of species in question. Therefore, researchers tend to vary only presence/absence of the species and use only one (supposedly realistic) combination of their numbers in experiments. However, nonlinearities in density dependence, functional responses, interactions between natural enemies etc. are typical for such systems, and nonlinear models of population dynamics generally predict qualitatively different results, if initial absolute densities of the species studied differ, even if their relative densities are maintained. Therefore, testing combinations of natural enemies without varying their densities may not be sufficient. Here we test this prediction experimentally. We show that the population dynamics of a system consisting of 2 natural enemies (aphid predator Adalia bipunctata (L.), and aphid parasitoid, Aphidius colemani Viereck) and their shared prey (peach aphid, Myzus persicae Sulzer) are strongly affected by the absolute initial densities of the species in question. Even if their relative densities are kept constant, the natural enemy species or combination thereof that most effectively suppresses the prey may depend on the absolute initial densities used in the experiment. Future empirical studies of multiple predator – one prey interactions should therefore use a two-dimensional array of initial densities of the studied species. Varying only combinations of natural enemies without varying their densities is not sufficient and can lead to misleading results.

Ameixa, Olga M. C. C.; Messelink, Gerben J.; Kindlmann, Pavel

2013-01-01

186

Nonlinearities lead to qualitative differences in population dynamics of predator-prey systems.  

PubMed

Since typically there are many predators feeding on most herbivores in natural communities, understanding multiple predator effects is critical for both community and applied ecology. Experiments of multiple predator effects on prey populations are extremely demanding, as the number of treatments and the amount of labour associated with these experiments increases exponentially with the number of species in question. Therefore, researchers tend to vary only presence/absence of the species and use only one (supposedly realistic) combination of their numbers in experiments. However, nonlinearities in density dependence, functional responses, interactions between natural enemies etc. are typical for such systems, and nonlinear models of population dynamics generally predict qualitatively different results, if initial absolute densities of the species studied differ, even if their relative densities are maintained. Therefore, testing combinations of natural enemies without varying their densities may not be sufficient. Here we test this prediction experimentally. We show that the population dynamics of a system consisting of 2 natural enemies (aphid predator Adalia bipunctata (L.), and aphid parasitoid, Aphidius colemani Viereck) and their shared prey (peach aphid, Myzus persicae Sulzer) are strongly affected by the absolute initial densities of the species in question. Even if their relative densities are kept constant, the natural enemy species or combination thereof that most effectively suppresses the prey may depend on the absolute initial densities used in the experiment. Future empirical studies of multiple predator - one prey interactions should therefore use a two-dimensional array of initial densities of the studied species. Varying only combinations of natural enemies without varying their densities is not sufficient and can lead to misleading results. PMID:23638107

Ameixa, Olga M C C; Messelink, Gerben J; Kindlmann, Pavel

2013-04-25

187

Temperature-altered predator-prey dynamics in freshwater ponds in Arctic Greenland  

NASA Astrophysics Data System (ADS)

Temperature sets the pace of many biological processes including species interactions. Describing the response of terrestrial and aquatic habitats to climate warming therefore requires studies of cross-trophic level dynamics. I use freshwater pond ecosystems in Arctic Greenland to study how the thermal environment shapes interactions between predators and their prey. This system is of interest because warming trends are notable, freshwaters are responding rapidly and dynamically to changes in temperature, and the biology of freshwaters is intimately linked to the terrestrial environment. My focal species are the Arctic mosquito (Diptera: Culicidae, Aedes nigripes) and its invertebrate predator, a predaceous diving beetle (Coleoptera: Dytiscidae, Colymbetes dolabratus). Both species develop as larvae in snow-melt ponds in May and June. I used experimental and observational studies to test effects of temperature on larval mosquito growth rates and predation rates by C. dolabratus. Results indicate strong effects of temperature on growth rate and development time but weak effects of temperature on consumption of mosquitoes by their predators. Incorporation of measured temperature response functions into a mosquito demographic model will elucidate how mosquito population dynamics in Arctic Greenland may change with temperature. For example, warming increases growth rate and decreases development time of mosquito larvae, which shortens the time larvae are exposed to predation. Additionally, decreased development time leads to an earlier mosquito emergence, with potential consequences for the health of wildlife. Evaluation of this model will reveal the importance of considering cross-trophic level dynamics when predicting mosquito population response to warming. Future studies will address interesting properties emerging from modeling, such as how shorter development time affects adult size and fitness, and connecting results to terrestrial systems in Arctic Greenland.

Culler, L. E.; Ayres, M.

2011-12-01

188

Man-Computer Symbiosis Through Interactive Graphics: A Survey and Identification of Critical Research Areas.  

ERIC Educational Resources Information Center

|The purpose of this report was to determine the research areas that appear most critical to achieving man-computer symbiosis. An operational definition of man-computer symbiosis was developed by: (1) reviewing and summarizing what others have said about it, and (2) attempting to distinguish it from other types of man-computer relationships. From…

Knoop, Patricia A.

189

Reconsidering the importance of the past in predator-prey models: both numerical and functional responses depend on delayed prey densities.  

PubMed

We propose that delayed predator-prey models may provide superficially acceptable predictions for spurious reasons. Through experimentation and modelling, we offer a new approach: using a model experimental predator-prey system (the ciliates Didinium and Paramecium), we determine the influence of past-prey abundance at a fixed delay (approx. one generation) on both functional and numerical responses (i.e. the influence of present : past-prey abundance on ingestion and growth, respectively). We reveal a nonlinear influence of past-prey abundance on both responses, with the two responding differently. Including these responses in a model indicated that delay in the numerical response drives population oscillations, supporting the accepted (but untested) notion that reproduction, not feeding, is highly dependent on the past. We next indicate how delays impact short- and long-term population dynamics. Critically, we show that although superficially the standard (parsimonious) approach to modelling can reasonably fit independently obtained time-series data, it does so by relying on biologically unrealistic parameter values. By contrast, including our fully parametrized delayed density dependence provides a better fit, offering insights into underlying mechanisms. We therefore present a new approach to explore time-series data and a revised framework for further theoretical studies. PMID:23926152

Li, Jiqiu; Fenton, Andy; Kettley, Lee; Roberts, Phillip; Montagnes, David J S

2013-08-07

190

Schoolyard Symbiosis.  

ERIC Educational Resources Information Center

|Discusses different types of symbiosis--mutualism, commensalism, and parasitism--and examples of each type including lichens, legumes, mistletoe, and epiphytes. Describes how teachers can use these examples in the study of symbiosis which allows teachers to focus on many basic concepts in evolution, cell biology, ecology, and other fields of…

Allard, David W.

1996-01-01

191

Schoolyard Symbiosis.  

ERIC Educational Resources Information Center

Discusses different types of symbiosis--mutualism, commensalism, and parasitism--and examples of each type including lichens, legumes, mistletoe, and epiphytes. Describes how teachers can use these examples in the study of symbiosis which allows teachers to focus on many basic concepts in evolution, cell biology, ecology, and other fields of…

Allard, David W.

1996-01-01

192

Lectin\\/glycan interactions play a role in recognition in a coral\\/dinoflagellate symbiosis  

Microsoft Academic Search

Summary Recognition is an important stage in the establish- ment of highly specific mutualistic associations. Yet, for the majority of symbioses, very few of the mecha- nisms involved in recognition and specificity are known. In this study, we provide evidence for a rec- ognition mechanism at the onset of symbiosis between larvae of the coral Fungia scutaria and their endosymbiotic

Elisha M. Wood-Charlson; Lea L. Hollingsworth; Dave A. Krupp; Virginia M. Weis

2006-01-01

193

Predator–Prey Interactions Between Aggressive-Mimic Jumping Spiders (Salticidae) and Araneophagic Spitting Spiders (Scytodidae) from the Philippines  

Microsoft Academic Search

In Los Baños in the Philippines (Laguna, Luzon), Scytodes sp. indet. is a web-building spitting spider (Scytodidae) that preys primarily on jumping spiders (Salticidae) and Portia labiata is an aggressive-mimic jumping spider that preys especially frequently on Scytodes. Tactics by which three species of Portia (P. africana, P. fimbriata, and P. labiata) and, for Portia labiata, three disjunct populations (Sri

Robert R. Jackson; Daiqin Li; Natasha Fijn; Alberto Barrion

1998-01-01

194

Influences of physical and chemical alterations on predator-prey interactions. [Largemouth bass; smallmouth bass; sauger; threadfin shad  

Microsoft Academic Search

These field studies have shown that impingement of fish at one steam plant is similar in three respects to predation of those fish by a natural predator. The similarities are (1) numbers of threadfin killed over time, (2) proportion of species killed, and (3) size classes of threadfin killed. We suggest that cold-induced behavioral changes and mortality of threadfin are

C. C. Coutant; R. B. McLean; D. L. DeAngelis

1978-01-01

195

Hydrodynamic patterns from fast-starts in teleost fish and their possible relevance to predator-prey interactions.  

PubMed

Fast-starts are distributed over a wide phylogenetic range of fish and are used for different purposes such as striking at prey or escaping from predators. Here we investigated 42 fast-starts of rainbow trouts (Oncorhynchus mykiss) elicited by a startle stimulus. We investigated the patterns of water movements left behind by the escaping fish and their possible value as a source of information to piscivorous predators that rely on hydrodynamic sensory systems. Particle image velocimetry (PIV) measurements revealed a temporal extension of up to 25.5 min and a spatial extension of up to 1.53 m (extrapolated) for a certain flow structure called jet 1, that is the flow produced by the tail fin. Duration and spatial extension of jet 2, the flow produced by the body, were on average lower, and both jets differed in size. The fish escaped in a mean direction approximately parallel to jet 1, and antiparallel to jet 2, with a range well above 200°. This study quantified the flow patterns generated by escaping fish and, as piscivorous predators would greatly benefit from being able to analyse these flow patterns, provides cues for the behavioural and physiological investigation of hydrodynamic sensory systems. PMID:23180046

Niesterok, Benedikt; Hanke, Wolf

2012-11-21

196

Understanding the importance of episodic acidification on fish predator-prey interactions: does weak acidification impair predator recognition?  

PubMed

The ability of prey to recognize predators is a fundamental prerequisite to avoid being eaten. Indeed, many prey animals learn to distinguish species that pose a threat from those that do not. Once the prey has learned the identity of one predator, it may generalize this recognition to similar predators with which the prey has no experience. The ability to generalize reduces the costs associated with learning and further enhances the ability of the prey to avoid relevant threats. For many aquatic organisms, recognition of predators is based on odor signatures, consequently any anthropogenic alteration in water chemistry has the potential to impair recognition and learning of predators. Here we explored whether episodic acidification could influence the ability of juvenile rainbow trout to learn to recognize an unknown predator and then generalize this recognition to a closely related predator. Trout were conditioned to recognize the odor of pumpkinseed sunfish under circumneutral (~pH 7) conditions, and then tested for recognition of pumpkinseed or longear sunfish under both neutral or weakly acidic (~pH 6) conditions. When tested for a response to pumpkinseed odor, we found no significant effect of predator odor pH: trout responded similarly regardless of pH. Moreover, under neutral conditions, trout were able to generalize their recognition to the odor of longear sunfish. However, the trout could not generalize their recognition of the longear sunfish under acidic conditions. Given the widespread occurrence of anthropogenic acidification, acid-mediated impairment of predator recognition and generalization may be a pervasive problem for freshwater salmonid populations and other aquatic organisms. PMID:23063639

Brown, Grant E; Elvidge, Chris K; Ferrari, Maud C O; Chivers, Douglas P

2012-10-11

197

Chemical cues from multiple predator-prey interactions induce changes in behavior and growth of anuran larvae  

Microsoft Academic Search

Chemical signals are used as information by prey to assess predation risk in their environment. To evaluate the effects of\\u000a multiple predators on prey growth, mediated by a change in prey activity, I exposed small and large bullfrog (Rana catesbeiana) larvae (tadpoles) to chemical cues from different combinations of bluegill sunfish (Lepomis macrochirus) and larval dragonfly (Anax junius) predators. Water

Peter Eklöv

2000-01-01

198

Predator-prey relations between age-1+ summer flounder (Paralichthys dentatus, Linnaeus) and age-0 winter flounder (Pseudopleuronectes americanus, Walbaum): predator diets, prey selection, and effects of sediments and macrophytes.  

PubMed

Laboratory experiments and weekly trammel net surveys in the Navesink River, New Jersey (USA) were used to examine the predator-prey interaction between age-1+ summer flounder (Paralichthys dentatus) and age-0 winter flounder (Pseudopleuronectes americanus). Winter flounder (24-67 mm TL) were the dominant piscine prey of summer flounder (n=95, 252-648 mm TL) collected in trammel nets. We observed a temporal shift in summer flounder diets from sand shrimp (Crangon septemspinosa) and winter flounder, dominant during June and early July, to blue crabs (Callinectes sapidus) and other fishes (primarily Atlantic silversides, Menidia menidia and Atlantic menhaden, Brevortia tyrannus) later in the summer. Variations in prey selection appeared to be related to changes in the spatial distribution of predators and spatio-temporal variation in prey availability. In laboratory experiments, summer flounder (271-345 mm total length, TL) preferred demersal winter flounder to a pelagic fish (Atlantic silversides) and a benthic invertebrate (sand shrimp) prey, and the vulnerability of winter flounder increased with increasing prey body size from 20 to 90 mm TL. Experiments testing habitat effects showed that mortality of winter flounder in three different size classes (20-29, 40-49, 60-69 mm TL) was not influenced by sediment grain sizes permitting differential burial of the prey. However, vegetation enhanced survival, with fish suffering lower mortality in eelgrass (Zostera marina, 15+/-0.04%) than in sea lettuce (Ulva lactuca, 38+/-0.04%) or bare sand (70+/-0.07%) when the macrophytes were planted to produce similar leaf surface areas (5000 cm(2) m(-2)). Prey vulnerability appeared to be related to the role of vision in the predator's attack strategy and prey activity levels. PMID:10958899

Manderson; Phelan; Stoner; Hilbert

2000-08-23

199

Neo-Symbiosis: The Next Stage in the Evolution of Human Information Interaction  

SciTech Connect

Abstract--The purpose of this paper is to re-address the vision of human-computer symbiosis as originally expressed by J.C.R. Licklider nearly a half-century ago. We describe this vision, place it in some historical context relating to the evolution of human factors research, and we observe that the field is now in the process of re-invigorating Licklider’s vision. We briefly assess the state of the technology within the context of contemporary theory and practice, and we describe what we regard as this emerging field of neo-symbiosis. We offer some initial thoughts on requirements to define functionality of neo-symbiotic systems and discuss research challenges associated with their development and evaluation.

Griffith, Douglas; Greitzer, Frank L.

2007-01-01

200

Man-Computer Symbiosis  

Microsoft Academic Search

Man-computer symbiosis is an expected development in cooperative interaction between men and electronic computers. It will involve very close coupling between the human and the electronic members of the partnership. The main aims are 1) to let computers facilitate formulative thinking as they now facilitate the solution of formulated problems, and 2) to enable men and computers to cooperate in

J. C. R. Licklider

1960-01-01

201

Simulation model of a predator-prey system comprised of Phytoseiulus persimilis and Tetranychus urticae . II. Model sensitivity to variations in the life history parameters of both species and to variations in the functional response and components of the numerical response  

Microsoft Academic Search

Summary  A detailed sensitivity analysis of a model of a predator-prey system comprised ofTetranychus urticae andPhytoseiulus persimilis was performed. The aim was to assess the relative importance of the life history parameters of both species, the functional\\u000a response, and the components of the numerical response. In addition, the impact of the initial predator-prey ratio and the\\u000a timing of predator introduction were

Peter B. Shaw

1985-01-01

202

Teaching Symbiosis.  

ERIC Educational Resources Information Center

|Argues that the meaning of the word "symbiosis" be standardized and that it should be used in a broad sense. Also criticizes the orthodox teaching of general principles in this subject and recommends that priority be given to continuity, intimacy, and associated adaptations, rather than to the harm/benefit relationship. (Author/JN)|

Harper, G. H.

1985-01-01

203

The Role of Zonal Flows and Predator-Prey Oscillations in Triggering the L-H Transition and in Internal Transport Barriers  

NASA Astrophysics Data System (ADS)

Low frequency Zonal Flows (ZFs) have been observed to trigger the L-H transition near the power threshold, by either an extended predator-prey limit cycle oscillation (LCO [1]) or a short (˜0.5-1.5 ms) ZF burst executing only part of one limit cycle. Localized turbulence suppression (k??s˜0.5) is initiated as the ZF shearing rate approaches the turbulence decorrelation rate. Turbulence-flow correlations (via Doppler Backscattering) show that the ZF amplitude and shear initially lag the rms fluctuation level by 90^o during LCO, transitioning to 180^o as the increasing ion pressure gradient and resulting equilibrium ExB shear secure the final transition to ELM-free H-mode. In a separate experiment, localized suppression of electron-scale fluctuations (k??s˜3) by ZF shear is also observed in an internal thermal electron transport barrier. However, in contrast to the L-H transition, here the density fluctuation level is always anti-correlated (180^o out of phase) with the ZF shearing rate. 4pt[1] L. Schmitz et al., Phys. Rev. Lett. 108, 155002 (2012).

Schmitz, L.; Zeng, L.; Rhodes, T. L.; Hillesheim, J. C.; Peebles, W. A.; McKee, G. R.; Yan, Z.; Groebner, R. J.; Burrell, K. H.; Tynan, G. R.; Boedo, J. A.; Solomon, W. M.

2012-10-01

204

Multiple limit cycles in a Gause type predator-prey model with Holling type III functional response and Allee effect on prey.  

PubMed

This work aims to examine the global behavior of a Gause type predator-prey model considering two aspects: (i) the functional response is Holling type III and, (ii) the prey growth is affected by the Allee effect. We prove the origin of the system is an attractor equilibrium point for all parameter values. It has also been shown that it is the ?-limit of a wide set of trajectories of the system, due to the existence of a separatrix curve determined by the stable manifold of the equilibrium point (m,0), which is associated to the Allee effect on prey. When a weak Allee effect on the prey is assumed, an important result is obtained, involving the existence of two limit cycles surrounding a unique positive equilibrium point: the innermost cycle is unstable and the outermost stable. This property, not yet reported in models considering a sigmoid functional response, is an important aspect for ecologists to acknowledge as regards the kind of tristability shown here: (1) the origin; (2) an interior equilibrium; and (3) a limit cycle of large amplitude. These models have undoubtedly been rather sensitive to disturbances and require careful management in applied conservation and renewable resource contexts. PMID:20830610

González-Olivares, Eduardo; Rojas-Palma, Alejandro

2010-09-10

205

Uniqueness of limit cycles and multiple attractors in a Gause-type predator-prey model with nonmonotonic functional response and Allee effect on prey.  

PubMed

The main purpose of this work is to analyze a Gause type predator-prey model in which two ecological phenomena are considered: the Allee effect affecting the prey growth function and the formation of group defence by prey in order to avoid the predation. We prove the existence of a separatrix curves in the phase plane, determined by the stable manifold of the equilibrium point associated to the Allee effect, implying that the solutions are highly sensitive to the initial conditions. Trajectories starting at one side of this separatrix curve have the equilibrium point (0,0) as their ?-limit, while trajectories starting at the other side will approach to one of the following three attractors: a stable limit cycle, a stable coexistence point or the stable equilibrium point (K,0) in which the predators disappear and prey attains their carrying capacity. We obtain conditions on the parameter values for the existence of one or two positive hyperbolic equilibrium points and the existence of a limit cycle surrounding one of them. Both ecological processes under study, namely the nonmonotonic functional response and the Allee effect on prey, exert a strong influence on the system dynamics, resulting in multiple domains of attraction. Using Liapunov quantities we demonstrate the uniqueness of limit cycle, which constitutes one of the main differences with the model where the Allee effect is not considered. Computer simulations are also given in support of the conclusions. PMID:23458304

González-Olivares, Eduardo; González-Yañez, Betsabé; Mena-Lorca, Jaime; Flores, Jose D

2013-04-01

206

Protein co-evolution, co-adaptation and interactions.  

PubMed

Co-evolution has an important function in the evolution of species and it is clearly manifested in certain scenarios such as host-parasite and predator-prey interactions, symbiosis and mutualism. The extrapolation of the concepts and methodologies developed for the study of species co-evolution at the molecular level has prompted the development of a variety of computational methods able to predict protein interactions through the characteristics of co-evolution. Particularly successful have been those methods that predict interactions at the genomic level based on the detection of pairs of protein families with similar evolutionary histories (similarity of phylogenetic trees: mirrortree). Future advances in this field will require a better understanding of the molecular basis of the co-evolution of protein families. Thus, it will be important to decipher the molecular mechanisms underlying the similarity observed in phylogenetic trees of interacting proteins, distinguishing direct specific molecular interactions from other general functional constraints. In particular, it will be important to separate the effects of physical interactions within protein complexes ('co-adaptation') from other forces that, in a less specific way, can also create general patterns of co-evolution. PMID:18818697

Pazos, Florencio; Valencia, Alfonso

2008-09-25

207

Relational Biology of Symbiosis  

Microsoft Academic Search

I formulate in relational terms the ubiquitous biological interaction of symbiosis. I explicate the topology of the different\\u000a modes of relational interactions of (M, R)-networks, the entailment diagrams that model the host and the symbiont. These modes\\u000a all have biological realizations as various categories of symbiotic relationships, ranging from mutualism to parasitism to\\u000a infection.

A. H. Louie

2010-01-01

208

Symbiosis: An Evolutionary Innovator.  

ERIC Educational Resources Information Center

|Defines symbiosis and describes the connection between symbiosis and evolution, how it is described in science textbooks, and genetic variability. Discusses educational policy and science curriculum content. (YDS)|

Case, Emily

2003-01-01

209

The effects of mobility on the one-dimensional four-species cyclic predator-prey model  

NASA Astrophysics Data System (ADS)

The dynamics of a one-dimensional lattice composed of four species cyclically dominating each other is very much dependent on the rates of mobility in the system. We realize mobility as the exchange of two particles located at two nearest neighbor sites with some species dependent rate s. Allowing for only one particle per site, the different species interact cyclically, with species dependent consumption rate k, such that k + s <=1. When varying the exchange rates, we see vastly different behavior when compared to the three-species model. The patterns of domain growth and decay still show an overall power law behavior, however the fundamental trend of domain growth does not follow the three-species case. We also look at the space-time diagrams to see precisely how the domains form, grow, and decay.

Konrad, David; Pleimling, Michel

2012-02-01

210

Prey selection, vertical migrations and the impacts of harvesting upon the population dynamics of a predator-prey system.  

PubMed

A model is developed to describe the interaction between a predator and two prey types located in different regions. Conditions for stability and persistence are analysed. The effects of harvesting the predators are investigated by making the predator mortality rate habitat dependent. Results demonstrate that for any given set of parameter values there is a value of the intrinsic preference of the predator for each prey type at which the system undergoes a Hopf bifurcation. Above this critical value the system evolves towards a stable equilibrium, whereas below it, stable limit cycles arise by Hopf bifurcations. Simulations demonstrate that the presence of demographic stochasticity may destabilise oscillatory populations, thereby causing population extinctions. An application of the model to the foraging behaviour of North Sea cod is described. It is shown that if the preferred prey is more productive, it is likely that the equilibrium will be stable, whereas if the less preferred prey is more productive, populations are likely to display cycles and in the stochastic case become extinct. As cod fishing mortality is increased, the point of bifurcation and region of parameter space for which the system is unstable decreases. An increased understanding of how cod behave may enable fish stocks to be managed more successfully, for example by indicating where marine reserves should be placed. PMID:17443393

Edwards, Helen J; Dytham, Calvin; Pitchford, Jonathan W; Righton, David

2007-04-19

211

"Prey Play": Learning about Predators and Prey through an Interactive, Role-Play Game  

ERIC Educational Resources Information Center

|"Prey Play" is an interactive role-play activity that provides fifth-grade students with opportunities to examine predator-prey interactions. This four-part, role-play activity allows students to take on the role of a predator and prey as they reflect on the behaviors animals exhibit as they collect food and interact with one another, as well as…

Deaton, Cynthia C. M.; Dodd, Kristen; Drennon, Katherine; Nagle, Jack

2012-01-01

212

Spatial, temporal and spectral structure of the turbulence-flow interaction at the L-H transition  

NASA Astrophysics Data System (ADS)

The physical mechanisms behind the L-H transition have been experimentally studied in the TJ-II plasmas. The spatial, temporal and spectral structure of the interaction between turbulence and flows has been studied close to the L-H transition threshold conditions. The temporal dynamics of the turbulence-flow interaction displays a predator-prey relationship and both, radial outward and inward propagation velocities of the turbulence-flow front have been measured. Moreover, the turbulence scales involved in the energy transfer of the predator-prey process have been identified.

Estrada, T.; Ascasíbar, E.; Blanco, E.; Cappa, A.; Diamond, P. H.; Happel, T.; Hidalgo, C.; Liniers, M.; van Milligen, B. Ph; Pastor, I.; Tafalla, D.; the TJ-II Team

2012-12-01

213

Recent advances in legume-microbe interactions: recognition, defense response and symbiosis from a genomic perspective  

Technology Transfer Automated Retrieval System (TEKTRAN)

The ability of legumes to form symbiotic mutualistic relationships with certain bacteria in the Rhizobiales (collectively called rhizobia) and harness the ability of the bacteria to "fix" atmospheric N2 into ammonia has had a tremendous impact on natural and agricultural ecosystems. The interaction ...

214

Geographic divergence in a species-rich symbiosis: interactions between monterey pines and ectomycorrhizal fungi.  

PubMed

A key problem in evolutionary biology is to understand how multispecific networks are reshaped by evolutionary and coevolutionary processes as they spread across contrasting environments. To address this problem, we need studies that explicitly evaluate the multispecific guild structure of coevolutionary processes and some of their key outcomes such as local adaptation. We evaluated geographic variation in interactions between most extant native populations of Monterey pine (Pinus radiata) and the associated resistant-propagule community (RPC) of ectomycorrhizal (EM) fungi, using a reciprocal cross-inoculation experiment with all factorial combinations of plant genotypes and soils with fungal guilds from each population. Our results suggest that the pine populations have diverged in community composition of their RPC fungi, and have also diverged genetically in several traits related to interactions of seedlings with particular EM fungi, growth, and biomass allocation. Patterns of genetic variation among pine populations for compatibility with EM fungi differed for the three dominant species of EM fungi, suggesting that Monterey pines can evolve differently in their compatibility with different symbiont species. PMID:23185888

Hoeksema, Jason D; Hernandez, Jesus Vargas; Rogers, Deborah L; Mendoza, Luciana Luna; Thompson, John N

2012-10-01

215

Foraging behavior and prey interactions by a guild of predators on various lifestages of Bemisia tabaci  

Microsoft Academic Search

The sweetpotato whitefly, Bemisia tabaci (Gennadius) is fed on by a wide variety of generalist predators, but there is little information on these predator-prey interactions. A laboratory investigation was conducted to quantify the foraging behavior of the adults of five common whitefly predators presented with a surfeit of whitefly eggs, nymphs, and adults. The beetles, Hippodamia convergens Guérin-Méneville and Collops

James R. Hagler; Charles G. Jackson; Rufus Isaacs; Scott A. Machtley

216

Predator–prey interactions from in situ time-lapse observations of a sublittoral mussel bed in the Gulf of Trieste (Northern Adriatic)  

Microsoft Academic Search

Hexaplex trunculus (Linnaeus, 1758) is one of the most abundant and widespread muricid gastropods in the Northern Adriatic Sea, but relatively little is known about the feeding ecology of this predator. We examined the activity of H. trunculus on a sublittoral mussel bed at 24 m depth through in situ time-lapse observations and bulk samples. The camera photographed a 0.25 m2 section

Jennifer A. Sawyer; Martin Zuschin; Bettina Riedel; Michael Stachowitsch

2009-01-01

217

Predator–prey-scavenging interactions between Nucella lapillus, Carcinus maenas and Eulalia viridis all exploiting Mytilus galloprovincialis on a rocky shore recovering from tributyl-tin (TBT) pollution  

Microsoft Academic Search

In 2004, a study began on a small (25 individuals) population of Nucella lapillus on the south coast of England. Following the global ban of tributyl-tin in the same year, freed from “imposex”, the size of the population increased such that by August 2010 it comprised > 1240 individuals. On the groyne, N. lapillus fed on barnacles (Semibalanus balanoides) up to a

Brian Morton

2011-01-01

218

Experimental prey species preferences of Hexaplex trunculus (Gastropoda: Muricidae) and predator–prey interactions with the Black mussel Mytilus galloprovincialis (Bivalvia: Mytilidae)  

Microsoft Academic Search

Hexaplex\\u000a trunculus is one of the most widespread Mediterranean species of muricid gastropod and lives on rocky, sandy-mud and mud substrata.\\u000a Although common in the Adriatic Sea, relatively little is known about its ecology especially feeding behaviour. The aim of\\u000a this study was to explore the aspects of the feeding behaviour of H. trunculus using Arca noae, Modiolus barbatus and

Melita Peharda; Brian Morton

2006-01-01

219

How Symbiosis Creates Diversity  

ERIC Educational Resources Information Center

|Diversity in habitats on Earth is astounding--whether on land or in the sea--and this is in part due to symbiosis. The lesson described in this article helps students understand how symbiosis affects different organisms through a fun and engaging game where they match hosts and symbionts based on their respective needs. This 45-minute lesson is…

Lord, Joshua

2010-01-01

220

International Symbiosis Society  

NSDL National Science Digital Library

The International Symbiosis Society (ISS) "is primarily involved with the promotion of research and education in the growing field of symbiosis. The Society seeks also to build ongoing and useful communication between the many researchers working in the various sub-fields of symbiosis, as well as connect symbiologists to those in other areas of ecology and biological sciences generally." Hosted by Boston University, the ISS website contains information about membership, and the international journal _Symbiosis_. For authors interested in submitting a manuscript to the journal, the site provides brief, downloadable instructions. In addition, the site links to the websites of Society members working in a variety of areas including Bark Beetles/Fungi, Cyanobacterial Symbioses, Lichens, Marine Symbioses, Mycorhizae, and more. Also, be sure to check out the fascinating images in the Symbiosis Gallery! This site is also reviewed in the June 10, 2005 _NSDL Life Sciences Report_.

221

Computer symbiosis: Emergence of symbiotic behavior through evolution  

SciTech Connect

Symbiosis is altruistic cooperation between distinct species. It is one of the most effective evolutionary processes, but its dynamics are not well understood as yet. A simple model of symbiosis is introduced, where we consider interactions between hosts and parasites and also mutations of hosts and parasites. It is found that a symbiotic state emerges for a suitable range of mutation rates. The symbiotic state is not static, but dynamically oscillates. Harmful parasites violating symbiosis appear periodically, but are rapidly extinguished by hosts and other parasites, and the symbiotic state is recovered. The emergence of ''Tit for Tat'' strategy to maintain symbiosis is discussed. 4 figs.

Ikegami, Takashi; Kaneko, Kunihiko

1989-01-01

222

On Human Symbiosis and the Vicissitudes of Individuation. Infantile Psychosis, Volume 1.  

ERIC Educational Resources Information Center

|The concepts of symbiosis and separation-individuation are explained, and the symbiosis theory of infantile psychosis is presented. Diagnostic considerations and clinical cases of child psychosis are reviewed; prototypes of mother-child interaction are described; and therapy is discussed. A summary of the symbiosis theory and a bibliography of…

Mahler, Margaret S.

223

Flashlight Fish Symbiosis.  

National Technical Information Service (NTIS)

This project investigates the symbiosis between anomalopids (flashlight fishes) and their luminous bacteria symbionts. Anomalopid fishes harbor luminous bacterial symboints in large light organs located beneath the eyes. This association is one of the mos...

M. G. Haygood

1990-01-01

224

Symbiosis: Rich, Exciting, Neglected Topic  

ERIC Educational Resources Information Center

|Argues that the topic of symbiosis has been greatly neglected and underemphasized in general-biology textbooks. Discusses many types and examples of symbiosis, and provides an extensive bibliography of the literature related to this topic. (JR)|

Rowland, Jane Thomas

1974-01-01

225

A mutualism–parasitism continuum model and its application to plant–mycorrhizae interactions  

Microsoft Academic Search

We consider interactions between a symbiont and its host in the framework of the familiar Lotka–Volterra predator–prey model, modified to allow the symbiont to benefit the host. The model includes both benefits and costs to the interaction and spans the mutualism–parasitism continuum. We use this model to explore the shift from mutualism to parasitism in plant–mycorrhizae interactions across gradients of

Claudia Neuhauser; Joseph E. Fargione

2004-01-01

226

Trait-Mediated Indirect Interactions in a Simple Aquatic Food Web  

Microsoft Academic Search

This investigation examines the role of trait-mediated indirect interactions in a simple aquatic food web. We conducted the experiments in cattle watering tanks in order to establish whether competitive and predator-prey interactions between two species are affected by other species in the system; i.e., are pairwise interaction strengths affected by the background species assemblage? We examined the survival and growth

Scott D. Peacor; Earl E. Werner

1997-01-01

227

INDUSTRIAL SYMBIOSIS: Literature and Taxonomy  

Microsoft Academic Search

Abstract Industrial symbiosis, as part of the emerging field of industrial ecology, demands resolute attention to the flow of materials and energy through local and regional economies. Industrial symbiosis engages traditionally separate industries in a collective approach to competitive advantage involving physical exchange of materials, energy, water, and\\/or by-products. The keys to industrial symbiosis are collaboration and the synergistic possibilities

Marian R. Chertow

2000-01-01

228

On the spatial dynamics and oscillatory behavior of a predator-prey model based on cellular automata and local particle swarm optimization.  

PubMed

A two-dimensional lattice model based on Cellular Automata theory and swarm intelligence is used to study the spatial and population dynamics of a theoretical ecosystem. It is found that the social interactions among predators provoke the formation of clusters, and that by increasing the mobility of predators the model enters into an oscillatory behavior. PMID:23927834

Molina, Mario Martínez; Moreno-Armendáriz, Marco A; Carlos Seck Tuoh Mora, Juan

2013-08-06

229

Molecular diagnosis of a previously unreported predator–prey association in coffee: Karnyothrips flavipes Jones (Thysanoptera: Phlaeothripidae) predation on the coffee berry borer  

Microsoft Academic Search

The coffee berry borer, Hypothenemus hampei, is the most important pest of coffee throughout the world, causing losses estimated at US $500 million\\/year. The thrips Karnyothrips flavipes was observed for the first time feeding on immature stages of H. hampei in April 2008 from samples collected in the Kisii area of Western Kenya. Since the trophic interactions between H. hampei

Juliana Jaramillo; Eric G. Chapman; Fernando E. Vega; James D. Harwood

2010-01-01

230

Survival through Symbiosis.  

ERIC Educational Resources Information Center

Describes symbiosis and its significance in the day-to-day lives of plants and animals. Gives specific examples of mutualism, commensalism, and parasitism in the relationships among fungus and plant roots, animals and bacteria, birds and animals, fish, and predator and prey. (MDH)

Abdi, S. Wali

1992-01-01

231

Survival through Symbiosis.  

ERIC Educational Resources Information Center

|Describes symbiosis and its significance in the day-to-day lives of plants and animals. Gives specific examples of mutualism, commensalism, and parasitism in the relationships among fungus and plant roots, animals and bacteria, birds and animals, fish, and predator and prey. (MDH)|

Abdi, S. Wali

1992-01-01

232

Symbiosis-mediated outbreaks  

Technology Transfer Automated Retrieval System (TEKTRAN)

Symbiosis simply means "living together" and in its narrowest form can mean two species deriving mutual benefit from the association. Recent studies have made evident that insect associations with microorganisms can range the gamut from casual associations to obligate or context-dependent mutualisms...

233

Impairment of trophic interactions between zebrafish ( Danio rerio ) and midge larvae ( Chironomus riparius ) by chlorpyrifos  

Microsoft Academic Search

The effects of chemicals on biotic interactions, such as competition and predation, have rarely been investigated in aquatic\\u000a ecotoxicology. This study presents a new approach for the investigation of predator–prey interactions between zebrafish (Danio rerio) and midge larvae (Chironomus riparius) impaired by chlorpyrifos (CHP), a neurotoxic insecticide. With a simple experimental design including four different treatments:\\u000a (1) control, (2) predator

Miriam Langer-Jaesrich; Cornelia Kienle; Heinz-R. Köhler; Almut Gerhardt

2010-01-01

234

Interactions of biotic and abiotic environmental factors in an ectomycorrhizal symbiosis, and the potential for selection mosaics  

PubMed Central

Background Geographic selection mosaics, in which species exert different evolutionary impacts on each other in different environments, may drive diversification in coevolving species. We studied the potential for geographic selection mosaics in plant-mycorrhizal interactions by testing whether the interaction between bishop pine (Pinus muricata D. Don) and one of its common ectomycorrhizal fungi (Rhizopogon occidentalis Zeller and Dodge) varies in outcome, when different combinations of plant and fungal genotypes are tested under a range of different abiotic and biotic conditions. Results We used a 2 × 2 × 2 × 2 factorial experiment to test the main and interactive effects of plant lineage (two maternal seed families), fungal lineage (two spore collections), soil type (lab mix or field soil), and non-mycorrhizal microbes (with or without) on the performance of plants and fungi. Ecological outcomes, as assessed by plant and fungal performance, varied widely across experimental environments, including interactions between plant or fungal lineages and soil environmental factors. Conclusion These results show the potential for selection mosaics in plant-mycorrhizal interactions, and indicate that these interactions are likely to coevolve in different ways in different environments, even when initially the genotypes of the interacting species are the same across all environments. Hence, selection mosaics may be equally as effective as genetic differences among populations in driving divergent coevolution among populations of interacting species.

Piculell, Bridget J; Hoeksema, Jason D; Thompson, John N

2008-01-01

235

Interactions between cougars (Puma concolor) and gray wolves (Canis lupus) in Banff National Park, Alberta  

Microsoft Academic Search

Large carnivore populations are recovering in many protected areas in North America, but the effect of increasing carnivore numbers on existing predator-prey and predator-predator interactions is poorly understood. We studied diet and spatial overlap among cougars (Puma concolor) and gray wolves (Canis lupus) in Banff National Park, Alberta (1993-2004) to evaluate how wolf recovery in the park influenced diet choice

Andrea D. KORTELLO; Thomas E. HURD; Dennis L. MURRAY

2007-01-01

236

Crab: snail size-structured interactions and salt marsh predation gradients  

Microsoft Academic Search

We studied size-structured predator-prey interactions between blue crabs (Callinectes sapidus) and marsh periwinkles (Littoraria irrorata) with a combination of field studies, laboratory experiments and individual-based modeling. Size distributions of Littoraria differed among years at the same sites in a salt marsh and could largely be explained by dominance of strong cohorts in the population. At a given site, abundance increased

Daniel E. Schindler; Brett M. Johnson; Neil A. MacKay; Nicolaas Bouwes; James F. Kitchell

1994-01-01

237

Epidemics spreading in predator–prey systems  

Microsoft Academic Search

In this paper, we consider an ecosystem in which two disease-affected populations thrive and in which the epidemics can spread from one species to the other one by contact. The feasibility and stability conditions of the equilibria of the system are investigated analytically. The model does not possess Hopf bifurcations. Numerical simulations are performed to investigate the role of the

S. Chaudhuri; A. Costamagna; E. Venturino

2012-01-01

238

Topic 3: Toward Understanding the Role of Diet in Host–Parasite Interactions: The Case for Japanese Macaques  

Microsoft Academic Search

\\u000a Central to understanding animal ecology are interactions between consumers and the consumed, whether predator–prey, herbivore–plant,\\u000a or mycophage–mushroom. A wealth of information exists describing just such relationships (Stephens and Krebs 1986; Stephens\\u000a et al. 2007). The first systematic and naturalistic study of primates (Alouatta palliata: Carpenter 1934) reported a partial list of items consumed by howler monkeys. Since then, countless food

Andrew J. J. MacIntosh; Michael A. Huffman

239

State-dependent habitat selection games between predators and prey: the importance of behavioural interactions and expected lifetime reproductive success  

Microsoft Academic Search

The fitness of both prey and predators will be affected by the behaviour of conspecifics and other (predator or prey) species. However, little theory has considered the case where predators and prey respond to one another simultaneously. I present a framework that examines the impact of the predator-prey behavioural interactions (within and between species) in a state-dependent life-history context. I

Suzanne H. Alonzo

2002-01-01

240

Symbiosis catalyses niche expansion and diversification.  

PubMed

Interactions between species are important catalysts of the evolutionary processes that generate the remarkable diversity of life. Symbioses, conspicuous and inherently interesting forms of species interaction, are pervasive throughout the tree of life. However, nearly all studies of the impact of species interactions on diversification have concentrated on competition and predation leaving unclear the importance of symbiotic interaction. Here, I show that, as predicted by evolutionary theories of symbiosis and diversification, multiple origins of a key innovation, symbiosis between gall-inducing insects and fungi, catalysed both expansion in resource use (niche expansion) and diversification. Symbiotic lineages have undergone a more than sevenfold expansion in the range of host-plant taxa they use relative to lineages without such fungal symbionts, as defined by the genetic distance between host plants. Furthermore, symbiotic gall-inducing insects are more than 17 times as diverse as their non-symbiotic relatives. These results demonstrate that the evolution of symbiotic interaction leads to niche expansion, which in turn catalyses diversification. PMID:23390106

Joy, Jeffrey B

2013-02-06

241

Symbiosis, Empathy, Suicidal Behavior, and the Family.  

ERIC Educational Resources Information Center

|This paper discusses the theoretical concept of symbiosis, as described by Mahler and her co-workers, and its clinical applications in suicidal situations. Also, the practical implications of the concept of symbiosis for assessment and treatment are discussed (Author)|

Richman, Joseph

1978-01-01

242

Arbuscular mycorrhizal symbiosis decreases strigolactone production in tomato.  

PubMed

Strigolactones are a new class of plant hormones emerging as important signals in the control of plant architecture. In addition, they are key elements in plant communication with several rhizosphere organisms. Strigolactones are exuded into the soil, where they act as host detection signals for arbuscular mycorrhizal (AM) fungi, but also as germination stimulants for root parasitic plant seeds. Under phosphate limiting conditions, plants up-regulate the secretion of strigolactones into the rhizosphere to promote the formation of AM symbiosis. Using tomato as a model plant, we have recently shown that AM symbiosis induces changes in transcriptional and hormonal profiles. Using the same model system, here we analytically demonstrate, using liquid chromatography-tandem mass spectrometry, that strigolactone production is also significantly reduced upon AM symbiosis. Considering the dual role of the strigolactones in the rhizosphere as signals for AM fungi and parasitic plants, we discuss the potential implications of these changes in the plant interaction with both organisms. PMID:20934776

López-Ráez, Juan A; Charnikhova, Tatsiana; Fernández, Ivan; Bouwmeester, Harro; Pozo, Maria J

2011-02-15

243

Molecular and cell biology of arbuscular mycorrhizal symbiosis  

Microsoft Academic Search

The roots of most extant plants are able to become engaged in an interaction with a small group of fungi of the fungal order Glomales (Glomeromycota). This interaction—arbuscular mycorrhizal (AM) symbiosis—is the evolutionary precursor of most other mutualistic root-microbe associations. The molecular analysis of this interaction can elucidate basic principles regarding such associations. This review summarizes our present knowledge about

Bettina Hause; Thomas Fester

2005-01-01

244

Mastering ectomycorrhizal symbiosis: the impact of carbohydrates.  

PubMed

Mycorrhiza formation is the consequence of a mutualistic interaction between certain soil fungi and plant roots that helps to overcome nutritional limitations faced by the respective partners. In symbiosis, fungi contribute to tree nutrition by means of mineral weathering and mobilization of nutrients from organic matter, and obtain plant-derived carbohydrates as a response. Support with easily degradable carbohydrates seems to be the driving force for fungi to undergo this type of interaction. As a consequence, the fungal hexose uptake capacity is strongly increased in Hartig net hyphae of the model fungi Amanita muscaria and Laccaria bicolor. Next to fast carbohydrate uptake and metabolism, storage carbohydrates are of special interest. In functional A. muscaria ectomycorrhizas, expression and activity of proteins involved in trehalose biosynthesis is mainly localized in hyphae of the Hartig net, indicating an important function of trehalose in generation of a strong carbon sink by fungal hyphae. In symbiosis, fungal partners receive up to approximately 19 times more carbohydrates from their hosts than normal leakage of the root system would cause, resulting in a strong carbohydrate demand of infected roots and, as a consequence, a more efficient plant photosynthesis. To avoid fungal parasitism, the plant seems to have developed mechanisms to control carbohydrate drain towards the fungal partner and link it to the fungus-derived mineral nutrition. In this contribution, current knowledge on fungal strategies to obtain carbohydrates from its host and plant strategies to enable, but also to control and restrict (under certain conditions), carbon transfer are summarized. PMID:18272925

Nehls, Uwe

2008-02-13

245

Auxin influences strigolactones in pea mycorrhizal symbiosis.  

PubMed

Hormone interactions are essential for the control of many developmental processes, including intracellular symbioses. The interaction between auxin and the new plant hormone strigolactone in the regulation of arbuscular mycorrhizal symbiosis was examined in one of the few auxin deficient mutants available in a mycorrhizal species, the auxin-deficient bsh mutant of pea (Pisum sativum). Mycorrhizal colonisation with the fungus Glomus intraradices was significantly reduced in the low auxin bsh mutant. The bsh mutant also exhibited a reduction in strigolactone exudation and the expression of a key strigolactone biosynthesis gene (PsCCD8). Strigolactone exudation was also reduced in wild type plants when the auxin content was reduced by stem girdling. Low strigolactone levels appear to be at least partially responsible for the reduced colonisation of the bsh mutant, as application of the synthetic strigolactone GR24 could partially rescue the mycorrhizal phenotype of bsh mutants. Data presented here indicates root auxin content was correlated with strigolactone exudation in both mutant and wild type plants. Mutant studies suggest that auxin may regulate early events in the formation of arbuscular mycorrhizal symbiosis by controlling strigolactone levels, both in the rhizosphere and possibly during early root colonisation. PMID:23219475

Foo, E

2012-12-06

246

Allometric functional response model: body masses constrain interaction strengths.  

PubMed

1. Functional responses quantify the per capita consumption rates of predators depending on prey density. The parameters of these nonlinear interaction strength models were recently used as successful proxies for predicting population dynamics, food-web topology and stability. 2. This study addressed systematic effects of predator and prey body masses on the functional response parameters handling time, instantaneous search coefficient (attack coefficient) and a scaling exponent converting type II into type III functional responses. To fully explore the possible combinations of predator and prey body masses, we studied the functional responses of 13 predator species (ground beetles and wolf spiders) on one small and one large prey resulting in 26 functional responses. 3. We found (i) a power-law decrease of handling time with predator mass with an exponent of -0.94; (ii) an increase of handling time with prey mass (power-law with an exponent of 0.83, but only three prey sizes were included); (iii) a hump-shaped relationship between instantaneous search coefficients and predator-prey body-mass ratios; and (iv) low scaling exponents for low predator-prey body mass ratios in contrast to high scaling exponents for high predator-prey body-mass ratios. 4. These scaling relationships suggest that nonlinear interaction strengths can be predicted by knowledge of predator and prey body masses. Our results imply that predators of intermediate size impose stronger per capita top-down interaction strengths on a prey than smaller or larger predators. Moreover, the stability of population and food-web dynamics should increase with increasing body-mass ratios in consequence of increases in the scaling exponents. 5. Integrating these scaling relationships into population models will allow predicting energy fluxes, food-web structures and the distribution of interaction strengths across food web links based on knowledge of the species' body masses. PMID:19845811

Vucic-Pestic, Olivera; Rall, Björn C; Kalinkat, Gregor; Brose, Ulrich

2009-10-20

247

Symbiosis: nursing and the bioengineer.  

PubMed

At this time, bioinstrumentation is the product of the possible as modified by what is practical. The bioengineer offers both the possible and the practical from an engineering and ideal model. The nurse, in contrast, speaks to the ideal possible from a confining practical clinical model. Symbiosis of nursing and bioengineering will combine the important attributes of each discipline for the betterment of patient care. In truth, the machine becomes an instrument of humanity. PMID:252712

Lenihan, J M; Abbey, J C

1978-12-01

248

Cell biology of cnidarian-dinoflagellate symbiosis.  

PubMed

The symbiosis between cnidarians (e.g., corals or sea anemones) and intracellular dinoflagellate algae of the genus Symbiodinium is of immense ecological importance. In particular, this symbiosis promotes the growth and survival of reef corals in nutrient-poor tropical waters; indeed, coral reefs could not exist without this symbiosis. However, our fundamental understanding of the cnidarian-dinoflagellate symbiosis and of its links to coral calcification remains poor. Here we review what we currently know about the cell biology of cnidarian-dinoflagellate symbiosis. In doing so, we aim to refocus attention on fundamental cellular aspects that have been somewhat neglected since the early to mid-1980s, when a more ecological approach began to dominate. We review the four major processes that we believe underlie the various phases of establishment and persistence in the cnidarian/coral-dinoflagellate symbiosis: (i) recognition and phagocytosis, (ii) regulation of host-symbiont biomass, (iii) metabolic exchange and nutrient trafficking, and (iv) calcification. Where appropriate, we draw upon examples from a range of cnidarian-alga symbioses, including the symbiosis between green Hydra and its intracellular chlorophyte symbiont, which has considerable potential to inform our understanding of the cnidarian-dinoflagellate symbiosis. Ultimately, we provide a comprehensive overview of the history of the field, its current status, and where it should be going in the future. PMID:22688813

Davy, Simon K; Allemand, Denis; Weis, Virginia M

2012-06-01

249

Cell Biology of Cnidarian-Dinoflagellate Symbiosis  

PubMed Central

Summary: The symbiosis between cnidarians (e.g., corals or sea anemones) and intracellular dinoflagellate algae of the genus Symbiodinium is of immense ecological importance. In particular, this symbiosis promotes the growth and survival of reef corals in nutrient-poor tropical waters; indeed, coral reefs could not exist without this symbiosis. However, our fundamental understanding of the cnidarian-dinoflagellate symbiosis and of its links to coral calcification remains poor. Here we review what we currently know about the cell biology of cnidarian-dinoflagellate symbiosis. In doing so, we aim to refocus attention on fundamental cellular aspects that have been somewhat neglected since the early to mid-1980s, when a more ecological approach began to dominate. We review the four major processes that we believe underlie the various phases of establishment and persistence in the cnidarian/coral-dinoflagellate symbiosis: (i) recognition and phagocytosis, (ii) regulation of host-symbiont biomass, (iii) metabolic exchange and nutrient trafficking, and (iv) calcification. Where appropriate, we draw upon examples from a range of cnidarian-alga symbioses, including the symbiosis between green Hydra and its intracellular chlorophyte symbiont, which has considerable potential to inform our understanding of the cnidarian-dinoflagellate symbiosis. Ultimately, we provide a comprehensive overview of the history of the field, its current status, and where it should be going in the future.

Allemand, Denis; Weis, Virginia M.

2012-01-01

250

Science Shorts: How Symbiosis Creates Diversity  

NSDL National Science Digital Library

Diversity in habitats on Earth is astounding--whether on land or in the sea--and this is in part due to symbiosis. The lesson described in this article helps students understand how symbiosis affects different organisms through a fun and engaging game where

Lord, Joshua

2010-01-01

251

A novel reef coral symbiosis  

NASA Astrophysics Data System (ADS)

Reef building corals form close associations with unicellular microalgae, fungi, bacteria and archaea, some of which are symbiotic and which together form the coral holobiont. Associations with multicellular eukaryotes such as polychaete worms, bivalves and sponges are not generally considered to be symbiotic as the host responds to their presence by forming physical barriers with an active growth edge in the exoskeleton isolating the invader and, at a subcellular level, activating innate immune responses such as melanin deposition. This study describes a novel symbiosis between a newly described hydrozoan ( Zanclea margaritae sp. nov.) and the reef building coral Acropora muricata (= A. formosa), with the hydrozoan hydrorhiza ramifying throughout the coral tissues with no evidence of isolation or activation of the immune systems of the host. The hydrorhiza lacks a perisarc, which is typical of symbiotic species of this and related genera, including species that associate with other cnidarians such as octocorals. The symbiosis was observed at all sites investigated from two distant locations on the Great Barrier Reef, Australia, and appears to be host species specific, being found only in A. muricata and in none of 30 other species investigated at these sites. Not all colonies of A. muricata host the hydrozoans and both the prevalence within the coral population (mean = 66%) and density of emergent hydrozoan hydranths on the surface of the coral (mean = 4.3 cm-2, but up to 52 cm-2) vary between sites. The form of the symbiosis in terms of the mutualism-parasitism continuum is not known, although the hydrozoan possesses large stenotele nematocysts, which may be important for defence from predators and protozoan pathogens. This finding expands the known A. muricata holobiont and the association must be taken into account in future when determining the corals’ abilities to defend against predators and withstand stress.

Pantos, O.; Bythell, J. C.

2010-09-01

252

A secondary symbiosis in progress?  

PubMed

Algae have acquired plastids by developing an endosymbiotic relationship with either a cyanobacterium (primary endosymbiosis) or other eukaryotic algae (secondary endosymbiosis). We report a protist, which we tentatively refer to as Hatena, that hosts an endosymbiotic green algal partner but inherits it unevenly. The endosymbiosis causes drastic morphological changes to both the symbiont and the host cell architecture. This type of life cycle, in which endosymbiont integration has only partially converted the host from predator to autotroph, may represent an early stage of plastid acquisition through secondary symbiosis. PMID:16224014

Okamoto, Noriko; Inouye, Isao

2005-10-14

253

Arbuscular mycorrhizal symbiosis increases host plant acceptance and population growth rates of the two-spotted spider mite Tetranychus urticae  

Microsoft Academic Search

Most terrestrial plants live in symbiosis with arbuscular mycorrhizal (AM) fungi. Studies on the direct interaction between\\u000a plants and mycorrhizal fungi are numerous whereas studies on the indirect interaction between such fungi and herbivores feeding\\u000a on aboveground plant parts are scarce. We studied the impact of AM symbiosis on host plant choice and life history of an acarine\\u000a surface piercing-sucking

Daniela Hoffmann; Horst Vierheilig; Petra Riegler; Peter Schausberger

2009-01-01

254

Laser microdissection and its application to analyze gene expression in arbuscular mycorrhizal symbiosis.  

PubMed

Phosphorus is essential for plant growth, and in many soils phosphorus availability limits crop production. Most plants in natural ecosystems obtain phosphorus via a symbiotic partnership with arbuscular mycorrhizal (AM) fungi. While the significance of these associations is apparent, their molecular basis is poorly understood. Consequently, the potential to harness the mycorrhizal symbiosis to improve phosphorus nutrition in agriculture is not realized. Transcript profiling has recently been used to investigate gene expression changes that accompany development of the AM symbiosis. While these approaches have enabled the identification of AM-symbiosis-associated genes, they have generally involved the use of RNA from whole mycorrhizal roots. Laser microdissection techniques allow the dissection and capture of individual cells from a tissue. RNA can then be isolated from these samples and cell-type specific gene expression information can be obtained. This technology has been applied to obtain cells from plants and more recently to study plant-microbe interactions. The latter techniques, particularly those developed for root-microbe interactions, are of relevance to plant-parasitic weed research. Here, laser microdissection, its use in plant biology and in particular plant-microbe interactions are discussed. An overview of the AM symbiosis is then provided, with a focus on recent advances in understanding development of the arbuscule-cortical cell interface. Finally, the recent applications of laser microdissection for analyses of AM symbiosis are discussed. PMID:19206091

Gomez, S Karen; Harrison, Maria J

2009-05-01

255

Symbiosis.  

ERIC Educational Resources Information Center

|Exposing today's students to a balance of science and the outside world is critical. The outdoors provides a context for practical applications of science, exposing the relevance of science to everyday life. Outdoor education instills an awareness that the health of the environment is directly coupled with our own health, enabling us to make…

Bicevskis, Rob

2002-01-01

256

Friend or foe? A behavioral and stable isotopic investigation of an ant–plant symbiosis  

Microsoft Academic Search

In ant–plant symbioses, the behavior of ant inhabitants affects the nature of the interaction, ranging from mutualism to parasitism. Mutualistic species confer a benefit to the plant, while parasites reap the benefits of the interaction without reciprocating, potentially resulting in a negative impact on the host plant. Using the ant–plant symbiosis between Cordia alliodora and its ant inhabitants as a

Chadwick V. Tillberg

2004-01-01

257

Noise-guided evolution within cyclical interactions  

Microsoft Academic Search

We study a stochastic predator prey model on a square lattice, where each of the six species has two superior and two inferior partners. The invasion probabilities between species depend on the predator prey pair and are supplemented by Gaussian noise. Conditions are identified that warrant the largest impact of noise on the evolutionary process, and the results of Monte

Matjaz Perc; Attila Szolnoki

2007-01-01

258

Consequences of symbiosis for food web dynamics.  

PubMed

Basic Lotka-Volterra type models in which mutualism (a type of symbiosis where the two populations benefit both) is taken into account, may give unbounded solutions. We exclude such behaviour using explicit mass balances and study the consequences of symbiosis for the long-term dynamic behaviour of a three species system, two prey and one predator species in the chemostat. We compose a theoretical food web where a predator feeds on two prey species that have a symbiotic relationships. In addition to a species-specific resource, the two prey populations consume the products of the partner population as well. In turn, a common predator forages on these prey populations. The temporal change in the biomass and the nutrient densities in the reactor is described by ordinary differential equations (ODE). Since products are recycled, the dynamics of these abiotic materials must be taken into account as well, and they are described by odes in a similar way as the abiotic nutrients. We use numerical bifurcation analysis to assess the long-term dynamic behaviour for varying degrees of symbiosis. Attractors can be equilibria, limit cycles and chaotic attractors depending on the control parameters of the chemostat reactor. These control parameters that can be experimentally manipulated are the nutrient density of the inflow medium and the dilution rate. Bifurcation diagrams for the three species web with a facultative symbiotic association between the two prey populations, are similar to that of a bi-trophic food chain; nutrient enrichment leads to oscillatory behaviour. Predation combined with obligatory symbiotic prey-interactions has a stabilizing effect, that is, there is stable coexistence in a larger part of the parameter space than for a bi-trophic food chain. However, combined with a large growth rate of the predator, the food web can persist only in a relatively small region of the parameter space. Then, two zero-pair bifurcation points are the organizing centers. In each of these points, in addition to a tangent, transcritical and Hopf bifurcation a global heteroclinic bifurcation is emanating. This heteroclinic cycle connects two saddle equilibria where the predator is absent. Under parameter variation the period of the stable limit cycle goes to infinity and the cycle tends to the heteroclinic cycle. At this global bifurcation point this cycle breaks and the boundary of the basin of attraction disappears abruptly because the separatrix disappears together with the cycle. As a result, it becomes possible that a stable two-nutrient-two-prey population system becomes unstable by invasion of a predator and eventually the predator goes extinct together with the two prey populations, that is, the complete food web is destroyed. This is a form of over-exploitation by the predator population of the two symbiotic prey populations. When obligatory symbiotic prey-interactions are modelled with Liebig's minimum law, where growth is limited by the most limiting resource, more complicated types of bifurcations are found. This results from the fact that the Jacobian matrix changes discontinuously with respect to a varying parameter when another resource becomes most limiting. PMID:15293013

Kooi, B W; Kuijper, L D J; Kooijman, S A L M

2004-01-02

259

Rhizobium-legume symbiosis shares an exocytotic pathway required for arbuscule formation  

PubMed Central

Endosymbiotic interactions are characterized by the formation of specialized membrane compartments, by the host in which the microbes are hosted, in an intracellular manner. Two well-studied examples, which are of major agricultural and ecological importance, are the widespread arbuscular mycorrhizal symbiosis and the Rhizobium–legume symbiosis. In both symbioses, the specialized host membrane that surrounds the microbes forms a symbiotic interface, which facilitates the exchange of, for example, nutrients in a controlled manner and, therefore, forms the heart of endosymbiosis. Despite their key importance, the molecular and cellular mechanisms underlying the formation of these membrane interfaces are largely unknown. Recent studies strongly suggest that the Rhizobium–legume symbiosis coopted a signaling pathway, including receptor, from the more ancient arbuscular mycorrhizal symbiosis to form a symbiotic interface. Here, we show that two highly homologous exocytotic vesicle-associated membrane proteins (VAMPs) are required for formation of the symbiotic membrane interface in both interactions. Silencing of these Medicago VAMP72 genes has a minor effect on nonsymbiotic plant development and nodule formation. However, it blocks symbiosome as well as arbuscule formation, whereas root colonization by the microbes is not affected. Identification of these VAMP72s as common symbiotic regulators in exocytotic vesicle trafficking suggests that the ancient exocytotic pathway forming the periarbuscular membrane compartment has also been coopted in the Rhizobium–legume symbiosis.

Ivanov, Sergey; Fedorova, Elena E.; Limpens, Erik; De Mita, Stephane; Genre, Andrea; Bonfante, Paola; Bisseling, Ton

2012-01-01

260

Rhizobium-legume symbiosis shares an exocytotic pathway required for arbuscule formation.  

PubMed

Endosymbiotic interactions are characterized by the formation of specialized membrane compartments, by the host in which the microbes are hosted, in an intracellular manner. Two well-studied examples, which are of major agricultural and ecological importance, are the widespread arbuscular mycorrhizal symbiosis and the Rhizobium-legume symbiosis. In both symbioses, the specialized host membrane that surrounds the microbes forms a symbiotic interface, which facilitates the exchange of, for example, nutrients in a controlled manner and, therefore, forms the heart of endosymbiosis. Despite their key importance, the molecular and cellular mechanisms underlying the formation of these membrane interfaces are largely unknown. Recent studies strongly suggest that the Rhizobium-legume symbiosis coopted a signaling pathway, including receptor, from the more ancient arbuscular mycorrhizal symbiosis to form a symbiotic interface. Here, we show that two highly homologous exocytotic vesicle-associated membrane proteins (VAMPs) are required for formation of the symbiotic membrane interface in both interactions. Silencing of these Medicago VAMP72 genes has a minor effect on nonsymbiotic plant development and nodule formation. However, it blocks symbiosome as well as arbuscule formation, whereas root colonization by the microbes is not affected. Identification of these VAMP72s as common symbiotic regulators in exocytotic vesicle trafficking suggests that the ancient exocytotic pathway forming the periarbuscular membrane compartment has also been coopted in the Rhizobium-legume symbiosis. PMID:22566631

Ivanov, Sergey; Fedorova, Elena E; Limpens, Erik; De Mita, Stephane; Genre, Andrea; Bonfante, Paola; Bisseling, Ton

2012-05-07

261

Symbiosis-related pea genes modulate fungal and plant gene expression during the arbuscule stage of mycorrhiza with Glomus intraradices  

Microsoft Academic Search

The arbuscular mycorrhiza association results from a successful interaction between genomes of the plant and fungal symbiotic\\u000a partners. In this study, we analyzed the effect of inactivation of late-stage symbiosis-related pea genes on symbiosis-associated\\u000a fungal and plant molecular responses in order to gain insight into their role in the functional mycorrhizal association. The\\u000a expression of a subset of ten fungal

Elena Kuznetsova; Pascale M. A. Seddas-Dozolme; Christine Arnould; Marie Tollot; Diederik van Tuinen; Alexey Borisov; Silvio Gianinazzi; Vivienne Gianinazzi-Pearson

2010-01-01

262

Elevated Temperature and Drought Interact to Reduce Parasitoid Effectiveness in Suppressing Hosts  

PubMed Central

Climate change affects the abundance, distribution and activity of natural enemies that are important for suppressing herbivore crop pests. Moreover, higher mean temperatures and increased frequency of climatic extremes are expected to induce different responses across trophic levels, potentially disrupting predator-prey interactions. Using field observations, we examined the response of an aphid host-parasitoid system to variation in temperature. Temperature was positively associated with attack rates by parasitoids, but also with a non-significant trend towards increased attack rates by higher-level hyperparasitoids. Elevated hyperparasitism could partly offset any benefit of climate warming to parasitoids, and would suggest that higher trophic levels may hamper predictions of predator-prey interactions. Additionally, the mechanisms affecting host-parasitoid dynamics were examined using controlled laboratory experiments that simulated both temperature increase and drought. Parasitoid fitness and longevity responded differently when exposed to each climatic variable in isolation, compared to the interaction of both variables at once. Although temperature increase or drought tended to positively affect the ability of parasitoids to control aphid populations, these effects were significantly reversed when the drivers were expressed in concert. Additionally, separate warming and drought treatments reduced parasitoid longevity, and although temperature increased parasitoid emergence success and drought increased offspring production, combined temperature and drought produced the lowest parasitoid emergence. The non-additive effects of different climate drivers, combined with differing responses across trophic levels, suggest that predicting future pest outbreaks will be more challenging than previously imagined.

Romo, Cecilia M.; Tylianakis, Jason M.

2013-01-01

263

The origin of new qualities in the evolution of interacting dynamical systems  

NASA Astrophysics Data System (ADS)

The principles of the emergence of new qualities are analyzed on the basis of the evolutionary analogies of biological systems and models of interacting systems. It is pointed out that competition does not create new qualities; it only elaborates on and disseminates a certain trait of the system. New qualities are generated by symbiotic interactions: mutualism, cooperation and predator-prey-like ones. Special attention is called to the evolution of the predator-prey-like system, as it evolves into an organized and even anticipatory system: when this system becomes a simple cybernetic regulator, when the predator specializes to process ~1 bit of information; when the system can regulate many parameters and the predator becomes a complex processor of information that controls the activity of the Prey, that is the transformations of matter/energy, when additional memory structures that contain fixed sets of programs emerge (programmed control); and when, finally, a special structure that can model the internal and external world and store information develops, and the whole system becomes an anticipatory system.

Kirvelis, Dobilas

1999-03-01

264

Predator-Prey Role Reversal in a Marine Benthic Ecosystem  

Microsoft Academic Search

Two closely located islands on the west coast of South Africa support widely different benthic communities. The biota at Malgas Island is dominated by seaweeds and by rock lobsters that consume settling mussels, thereby preventing the establishment of the mussels. They also prey on whelks, although one species, Burnupena papyracea, is protected from predation by a commensal bryozoan that covers

Amos Barkai; Christopher McQuaid

1988-01-01

265

Periodic travelling waves in cyclic predator-prey systems  

Microsoft Academic Search

Abstract Predation is an established cause of cycling in prey species. Here, the ability of predation to explain periodic travelling waves in prey populations, which have recently been found in a number of spatiotemporal field studies, is examined. The nature of periodic waves in these systems, and the way in which they can be generated by the invasion of predators

A. Sherratt

266

Red Queen dynamics in a predator-prey ecosystem  

Microsoft Academic Search

The probability of predation is maximal if both have the same phenotype, but decreases with the difference between phenotypes according to a Gaussian probability distribution. All individuals are speci ed with an inheritable phenotype. Phenotypes are natural values along a wrapped-around phe-notype space [0,100]. The minimal phenotypic difference is used to determine the probability of predation. Offspring have a small

Walter De Back; Marco Wiering; Edwin D. De Jong

2006-01-01

267

Effects of random habitat destruction in a predator prey model  

NASA Astrophysics Data System (ADS)

The influence of habitat destruction on a population of predators and prey is studied. We show, via Monte Carlo simulations of a lattice model, that with growing devastation the oscillations in the densities of both species, as well as cross-correlations between the two densities diminish. As should be expected, predators are more vulnerable and disappear before the prey. Devastation of the habitat is never beneficial and the percentage of coexisting (prey and predators) states decreases with destruction. Because of the high fragmentation of the environment in the case of large devastation, animals’ populations are separated into small sub-populations living in restricted areas. Such small populations become extinct more easily. We have also shown that in the case of large habitat devastation the density of the population of prey depends on its history.

Szwabi?ski, Janusz; Pe?alski, Andrzej

2006-01-01

268

Trait-mediated diversification in nematode predator-prey systems.  

PubMed

Nematodes are presumably the most numerous Metazoans in terrestrial habitats. They are represented at all trophic levels and are known to respond to nutrient limitation, prey availability, and microbial resources. Predatory nematodes reside at the highest trophic level, and as such their feeding habits could have a major impact on soil food web functioning. Here, we investigate the effects of gender and developmental stage on the nematode body sizes in coarse and loamy soils. Besides Neodiplogasteridae, our predators are much larger than other soil-dwelling nematodes from their early developmental stage onwards. From juvenile to adult, the predatory Aporcelaimellus (Kruskal-Wallis P < 0.001), Dorylaimoides, and Tripyla (both P < 0.01) show great length increases during their developmental growth, in contrast to their possible prey (almost all P < 0.001). Less than 4% of the prey exceeds the length of the predatory adults, but more than 30% of the prey exceeds the length of the predatory juveniles. Potential body size ratios and some physical problems experienced by small fluid feeders attacking large prey are discussed in an attempt to summarize different prey-searching mechanisms and aggregative predatory responses in the soil system. PMID:22393508

Mulder, Christian; Helder, Johannes; Vervoort, Mariëtte T W; Arie Vonk, J

2011-11-01

269

Trait-mediated diversification in nematode predator-prey systems  

PubMed Central

Nematodes are presumably the most numerous Metazoans in terrestrial habitats. They are represented at all trophic levels and are known to respond to nutrient limitation, prey availability, and microbial resources. Predatory nematodes reside at the highest trophic level, and as such their feeding habits could have a major impact on soil food web functioning. Here, we investigate the effects of gender and developmental stage on the nematode body sizes in coarse and loamy soils. Besides Neodiplogasteridae, our predators are much larger than other soil-dwelling nematodes from their early developmental stage onwards. From juvenile to adult, the predatory Aporcelaimellus (Kruskal–Wallis P < 0.001), Dorylaimoides, and Tripyla (both P < 0.01) show great length increases during their developmental growth, in contrast to their possible prey (almost all P < 0.001). Less than 4% of the prey exceeds the length of the predatory adults, but more than 30% of the prey exceeds the length of the predatory juveniles. Potential body size ratios and some physical problems experienced by small fluid feeders attacking large prey are discussed in an attempt to summarize different prey-searching mechanisms and aggregative predatory responses in the soil system.

Mulder, Christian; Helder, Johannes; Vervoort, Mariette T W; Arie Vonk, J

2011-01-01

270

The hydra effect in predator–prey models  

Microsoft Academic Search

The seemingly paradoxical increase of a species population size in response to an increase in its mortality rate has been\\u000a observed in several continuous-time and discrete-time models. This phenomenon has been termed the “hydra effect”. In light\\u000a of the fact that there is almost no empirical evidence yet for hydra effects in natural and laboratory populations, we address\\u000a the question

Michael Sieber; Frank M. Hilker

271

Predator-prey relationships among larval dragonflies, salamanders, and frogs  

Microsoft Academic Search

Tadpoles of the barking tree frog, Hyla gratiosa, are abundant in spring and summer in some ponds and Carolina bays on the Savannah River Plant near Aiken, South Carolina. To determine how these tadpoles survive in the presence of predaceous salamander larvae, Ambystoma talpoideum, and larvae of an aeshnid dragonfly, Anax junius, we determined fields densities and sizes of the

J. P. Caldwell; J. H. Thorp; T. O. Jervey

1980-01-01

272

A predator prey approach to the network structure of cyberspace  

Microsoft Academic Search

In light of the rise of malicious attacks on the Internet and the various networks and applications attached to it, new approaches towards modeling predatory activity in networks is called for. Past research has simulated networks assuming that all nodes are homogenously susceptible to attack or infection. Often times in real world networks only subsets of nodes are susceptible attack

Sean P. Gorman; Rajendra G. Kulkarni; Laurie A. Schintler; Roger R. Stough

2004-01-01

273

Developmental Insights into Evolving Systems: Roles of Diversity, Non-Selection, Self-Organization, Symbiosis  

Microsoft Academic Search

A developmental view of evolving systems (ecologi- cal, social, economical, organizational) is examined to clarify 1) the role of selection processes versus collec- tive, non-selective processes, 2) the origins of diversity and its role in system performance and robustness 3) the origin of explicit subsystem interactions (cooper- ation\\/symbiosis) that enhance individual and system performance, 4) the preconditions necessary for fur-

Norman L. Johnson

274

Augmentation, symbiosis, transcendence: technology and the future(s) of human identity  

Microsoft Academic Search

Accelerating and converging technological changes in several fields are now challenging fundamental assumptions about human nature in general and, more specifically, ideas about the sense of personal identity. Major themes in the emerging dialogue concerning this subject are: augmentation (creating abilities not biologically inherent in the phenotype), symbiosis (interaction between two organisms or between people and intelligent machines), and transcendence

Walter Truett Anderson

2003-01-01

275

The paradox of enrichment in phytoplankton by induced competitive interactions.  

PubMed

The biodiversity loss of phytoplankton with eutrophication has been reported in many aquatic ecosystems, e.g., water pollution and red tides. This phenomenon seems similar, but different from the paradox of enrichment via trophic interactions, e.g., predator-prey systems. We here propose the paradox of enrichment by induced competitive interactions using multiple contact process (a lattice Lotka-Volterra competition model). Simulation results demonstrate how eutrophication invokes more competitions in a competitive ecosystem resulting in the loss of phytoplankton diversity in ecological time. The paradox is enhanced under local interactions, indicating that the limited dispersal of phytoplankton reduces interspecific competition greatly. Thus, the paradox of enrichment appears when eutrophication destroys an ecosystem either by elevated interspecific competition within a trophic level and/or destabilization by trophic interactions. Unless eutrophication due to human activities is ceased, the world's aquatic ecosystems will be at risk. PMID:24089056

Tubay, Jerrold M; Ito, Hiromu; Uehara, Takashi; Kakishima, Satoshi; Morita, Satoru; Togashi, Tatsuya; Tainaka, Kei-Ichi; Niraula, Mohan P; Casareto, Beatriz E; Suzuki, Yoshimi; Yoshimura, Jin

2013-10-03

276

The paradox of enrichment in phytoplankton by induced competitive interactions  

PubMed Central

The biodiversity loss of phytoplankton with eutrophication has been reported in many aquatic ecosystems, e.g., water pollution and red tides. This phenomenon seems similar, but different from the paradox of enrichment via trophic interactions, e.g., predator-prey systems. We here propose the paradox of enrichment by induced competitive interactions using multiple contact process (a lattice Lotka-Volterra competition model). Simulation results demonstrate how eutrophication invokes more competitions in a competitive ecosystem resulting in the loss of phytoplankton diversity in ecological time. The paradox is enhanced under local interactions, indicating that the limited dispersal of phytoplankton reduces interspecific competition greatly. Thus, the paradox of enrichment appears when eutrophication destroys an ecosystem either by elevated interspecific competition within a trophic level and/or destabilization by trophic interactions. Unless eutrophication due to human activities is ceased, the world's aquatic ecosystems will be at risk.

Tubay, Jerrold M.; Ito, Hiromu; Uehara, Takashi; Kakishima, Satoshi; Morita, Satoru; Togashi, Tatsuya; Tainaka, Kei-ichi; Niraula, Mohan P.; Casareto, Beatriz E.; Suzuki, Yoshimi; Yoshimura, Jin

2013-01-01

277

CERBERUS and NSP1 of Lotus japonicus are Common Symbiosis Genes that Modulate Arbuscular Mycorrhiza Development.  

PubMed

Arbuscular mycorrhizal symbiosis (AMS) and root nodule symbiosis (RNS) are mutualistic plant-microbe interactions that confer nutritional benefits to both partners. Leguminous plants possess a common genetic system for intracellular symbiosis with AM fungi and with rhizobia. Here we show that CERBERUS and NSP1, which respectively encode an E3 ubiquitin ligase and a GRAS transcriptional regulator and which have previously only been implicated in RNS, are involved in AM fungal infection in Lotus japonicus. Hyphal elongation along the longitudinal axis of the root was reduced in the cerberus mutant, giving rise to a lower colonization level. Knockout of NSP1 decreased the frequency of plants colonized by AM fungi or rhizobia. CERBERUS and NSP1 showed different patterns of expression in response to infection with symbiotic microbes. A low constitutive level of CERBERUS expression was observed in the root and an increased level of NSP1 expression was detected in arbuscule-containing cells. Induction of AM marker gene was triggered in both cerberus and nsp1 mutants by infection with symbiotic microbes; however, the mutants showed a weaker induction of marker gene expression than the wild type, mirroring their lower level of colonization. The common symbiosis genes are believed to act in an early signaling pathway for recognition of symbionts and for triggering early symbiotic responses. Our quantitative analysis of symbiotic phenotypes revealed developmental defects of the novel common symbiosis mutants in both symbioses, which demonstrates that common symbiosis mechanisms also contribute to a range of functions at later or different stages of symbiont infection. PMID:23926062

Takeda, Naoya; Tsuzuki, Syusaku; Suzaki, Takuya; Parniske, Martin; Kawaguchi, Masayoshi

2013-08-07

278

Symbiosis and co-evolution in animats  

Microsoft Academic Search

This paper investigates the dynamics of co-evolution of various types of animats. For this purpose, we use a problem we call the Blind Hunger Dilemma. This problem investigates the emergence of collective behavior concerned with shared resource. Our model of co-evolution is inspired by Margulis's idea of parasitism and symbiosis which she applies to the origin of the current eukaryotic

Chisato Numaoka; Takanawa Muse

279

Positive indirect interactions between neighboring plant species via a lizard pollinator.  

PubMed

In natural communities, species are embedded in networks of direct and indirect interactions. Most studies on indirect interactions have focused on how they affect predator-prey or competitive relationships. However, it is equally likely that indirect interactions play an important structuring role in mutualistic relationships in a natural community. We demonstrate experimentally that on a small spatial scale, dense thickets of endemic Pandanus plants have a strong positive trait-mediated indirect effect on the reproduction of the declining endemic Mauritian plant Trochetia blackburniana. This effect is mediated by the endemic gecko Phelsuma cepediana moving between Pandanus thickets, a preferred microhabitat, and nearby T. blackburniana plants, where it feeds on nectar and pollinates the plants. Our findings emphasize the importance of considering plant-animal interactions such as pollination at relatively small spatial scales in both basic ecological studies and applied conservation management. PMID:17262697

Hansen, Dennis M; Kiesbüy, Heine C; Jones, Carl G; Müller, Christine B

2007-04-01

280

Long-distance transport of signals during symbiosis  

PubMed Central

Legumes enter nodule symbioses with nitrogen-fixing bacteria (rhizobia), whereas most flowering plants establish symbiotic associations with arbuscular mycorrhizal (AM) fungi. Once first steps of symbiosis are initiated, nodule formation and mycorrhization in legumes is negatively controlled by a shoot-derived inhibitor (SDI), a phenomenon termed autoregulation. According to current views, autoregulation of nodulation and mycorrhization in legumes is regulated in a similar way. CLE peptides induced in response to rhizobial nodulation signals (Nod factors) have been proposed to represent the ascending long-distance signals to the shoot. Although not proven yet, these CLE peptides are likely perceived by leucine-rich repeat (LRR) autoregulation receptor kinases in the shoot. Autoregulation of mycorrhization in non-legumes is reminiscent to the phenomenon of “systemic acquired resistance” in plant-pathogen interactions.

Xie, Zhi-Ping; Illana, Antonio

2011-01-01

281

Shifting species interactions in terrestrial dryland ecosystems under altered water availability and climate change.  

PubMed

Species interactions play key roles in linking the responses of populations, communities, and ecosystems to environmental change. For instance, species interactions are an important determinant of the complexity of changes in trophic biomass with variation in resources. Water resources are a major driver of terrestrial ecology and climate change is expected to greatly alter the distribution of this critical resource. While previous studies have documented strong effects of global environmental change on species interactions in general, responses can vary from region to region. Dryland ecosystems occupy more than one-third of the Earth's land mass, are greatly affected by changes in water availability, and are predicted to be hotspots of climate change. Thus, it is imperative to understand the effects of environmental change on these globally significant ecosystems. Here, we review studies of the responses of population-level plant-plant, plant-herbivore, and predator-prey interactions to changes in water availability in dryland environments in order to develop new hypotheses and predictions to guide future research. To help explain patterns of interaction outcomes, we developed a conceptual model that views interaction outcomes as shifting between (1) competition and facilitation (plant-plant), (2) herbivory, neutralism, or mutualism (plant-herbivore), or (3) neutralism and predation (predator-prey), as water availability crosses physiological, behavioural, or population-density thresholds. We link our conceptual model to hypothetical scenarios of current and future water availability to make testable predictions about the influence of changes in water availability on species interactions. We also examine potential implications of our conceptual model for the relative importance of top-down effects and the linearity of patterns of change in trophic biomass with changes in water availability. Finally, we highlight key research needs and some possible broader impacts of our findings. Overall, we hope to stimulate and guide future research that links changes in water availability to patterns of species interactions and the dynamics of populations and communities in dryland ecosystems. PMID:22098619

McCluney, Kevin E; Belnap, Jayne; Collins, Scott L; González, Angélica L; Hagen, Elizabeth M; Nathaniel Holland, J; Kotler, Burt P; Maestre, Fernando T; Smith, Stanley D; Wolf, Blair O

2011-11-17

282

Shifting species interactions in terrestrial dryland ecosystems under altered water availability and climate change  

USGS Publications Warehouse

Species interactions play key roles in linking the responses of populations, communities, and ecosystems to environmental change. For instance, species interactions are an important determinant of the complexity of changes in trophic biomass with variation in resources. Water resources are a major driver of terrestrial ecology and climate change is expected to greatly alter the distribution of this critical resource. While previous studies have documented strong effects of global environmental change on species interactions in general, responses can vary from region to region. Dryland ecosystems occupy more than one-third of the Earth's land mass, are greatly affected by changes in water availability, and are predicted to be hotspots of climate change. Thus, it is imperative to understand the effects of environmental change on these globally significant ecosystems. Here, we review studies of the responses of population-level plant-plant, plant-herbivore, and predator-prey interactions to changes in water availability in dryland environments in order to develop new hypotheses and predictions to guide future research. To help explain patterns of interaction outcomes, we developed a conceptual model that views interaction outcomes as shifting between (1) competition and facilitation (plant-plant), (2) herbivory, neutralism, or mutualism (plant-herbivore), or (3) neutralism and predation (predator-prey), as water availability crosses physiological, behavioural, or population-density thresholds. We link our conceptual model to hypothetical scenarios of current and future water availability to make testable predictions about the influence of changes in water availability on species interactions. We also examine potential implications of our conceptual model for the relative importance of top-down effects and the linearity of patterns of change in trophic biomass with changes in water availability. Finally, we highlight key research needs and some possible broader impacts of our findings. Overall, we hope to stimulate and guide future research that links changes in water availability to patterns of species interactions and the dynamics of populations and communities in dryland ecosystems.

McCluney, Kevin E.; Belnap, Jayne; Collins, Scott L.; González, Angélica L.; Hagen, Elizabeth M.; Holland, J. Nathaniel; Kotler, Burt P.; Maestre, Fernando T.; Smith, Stanley D.; Wolf, Blair O.

2012-01-01

283

Spatio-temporal dynamics of a three interacting species mathematical model inspired in physics  

NASA Astrophysics Data System (ADS)

In this paper we study both, analytically and numerically, the spatio-temporal dynamics of a three interacting species mathematical model. The populations take the form of pollinators, a plant and herbivores; the model consists of three nonlinear reaction-diffusion-advection equations. In view of considering the full model, as a previous step we firstly analyze a mutualistic interaction (pollinator-plant), later on a predator-prey (plant-herbivore) interaction model is studied and finally, we consider the full model. In all cases, the purely temporal dynamics is given; meanwhile for the spatio-temporal dynamics, we use numerical simulations, corresponding to those parameter values for which we obtain interesting temporal dynamics.

Sánchez-Garduño, Faustino; Breña-Medina, Víctor F.

2008-02-01

284

Signaling in Ectomycorrhizal Symbiosis Establishment  

Microsoft Academic Search

\\u000a For the ectomycorrhizal establishment, different signals must be exchanged between plants and fungal partners. After a brief\\u000a description of the ectomycorrhiza formation, the present chapter highlights the recent works on the nature of the signal molecules\\u000a involved in this type of plant–microbe interaction. Signals involved in the fungal spore germination and mycelium growth,\\u000a including the chemoattraction of the mycelium by

Paula Baptista; Rui Manuel Tavares; Teresa Lino-Neto

285

Coral life history and symbiosis: Functional genomic resources for two reef building Caribbean corals, Acropora palmata and Montastraea faveolata  

Microsoft Academic Search

BACKGROUND: Scleractinian corals are the foundation of reef ecosystems in tropical marine environments. Their great success is due to interactions with endosymbiotic dinoflagellates (Symbiodinium spp.), with which they are obligately symbiotic. To develop a foundation for studying coral biology and coral symbiosis, we have constructed a set of cDNA libraries and generated and annotated ESTs from two species of corals,

Jodi A Schwarz; Peter B Brokstein; Christian R Voolstra; Astrid Y Terry; David J Miller; Alina M Szmant; Mary ALICE Coffroth; Mónica Medina

2008-01-01

286

Potential Symbiosis-Specific Genes Uncovered by Sequencing a 410Kilobase DNA Region of the Bradyrhizobium japonicum Chromosome  

Microsoft Academic Search

The physical and genetic map of the Bradyrhizobium japonicum chromosome revealed that nitrogen fixation and nodulation genes are clustered. Because of the complex interactions between the bacterium and the plant, we expected this chromosomal sector to contain additional genes that are involved in the maintenance of an efficient symbiosis. Therefore, we determined the nucleotide sequence of a 410-kb region. The

MICHAEL GOTTFERT; SANDRA ROTHLISBERGER; CHRISTOPH KUNDIG; CHRISTOPH BECK; ROGER MARTY; HAUKE HENNECKE

2001-01-01

287

Exploiting an ancient signalling machinery to enjoy a nitrogen fixing symbiosis.  

PubMed

For almost a century now it has been speculated that a transfer of the largely legume-specific symbiosis with nitrogen fixing rhizobium would be profitable in agriculture [1,2]. Up to now such a step has not been achieved, despite intensive research in this era. Novel insights in the underlying signalling networks leading to intracellular accommodation of rhizobium as well as mycorrhizal fungi of the Glomeromycota order show extensive commonalities between both interactions. As mycorrhizae symbiosis can be established basically with most higher plant species it raises questions why is it only in a few taxonomic lineages that the underlying signalling network could be hijacked by rhizobium. Unravelling this will lead to insights that are essential to achieve an old dream. PMID:22633856

Geurts, Rene; Lillo, Alessandra; Bisseling, Ton

2012-05-26

288

Osmoregulation in anthozoan-dinoflagellate symbiosis.  

PubMed

Endosymbiosis creates a unique osmotic circumstance. Hosts are not only responsible for balancing their internal osmolarity with respect to the external environment, but they must also maintain a compatible osmotic environment for their endosymbionts, which may themselves contribute to the net osmolarity of the host cell through molecular fluxes and/or exchange. Cnidarian hosts that harbor intracellular dinoflagellates (zooxanthellae) are excellent examples of such a symbiosis. These associations are characterized by the exchange of osmotically active compounds, but they are temporally stable under normal environmental conditions indicating that these osmotically driven exchanges are effectively and rapidly regulated. Although we have some knowledge about how asymbiotic anthozoans and algae osmoregulate, our understanding of the physiological mechanisms involved in regulating an intact anthozoan-dinoflagellate symbiosis is poor. Large-scale expulsion of endosymbiotic zooxanthellae, or bleaching, is currently considered to be one of the greatest threats to coral reefs worldwide. To date, there has been little consideration of the osmotic scenarios that occur when these symbioses are exposed to the conditions that normally elicit bleaching, such as increased seawater temperatures and UV radiation. Here we review what is known about osmoregulation and osmotic stress in anthozoans and dinoflagellates and discuss the osmotic implications of exposure to environmental stress in these globally distributed and ecologically important symbioses. PMID:17317249

Mayfield, Anderson B; Gates, Ruth D

2007-01-16

289

Symbiosis as a mechanism of evolution: status of cell symbiosis theory.  

PubMed

Several theories for the origin of eukaryotic (nucleated) cells from prokaryotic (bacterial) ancestors have been published: the progenote, the direct filiation and the serial endosymbiotic theory (SET). Compelling evidence for two aspects of the SET is now available suggesting that both mitochondria and plastids originated by symbioses with a third type of microbe, probably a Thermoplasma-like archaebacterium ancestral to the nucleocytoplasm. We conclude that not enough information is available to negate or substantiate another SET hypothesis: that the undulipodia (cilia, eukaryotic flagella) evolved from spirochetes. Recognizing the power of symbiosis to recombine in single individual semes from widely differing partners, we develop the idea that symbiosis has been important in the origin of species and higher taxa. The abrupt origin of novel life forms through the formation of stable symbioses is consistent with certain patterns of evolution (e.g punctuated equilibria) described by some paleontologists. PMID:11543608

Margulis, L; Bermudes, D

1985-01-01

290

Spatiotemporal structure of the interaction between turbulence and flows at the L-H transition in a toroidal plasma.  

PubMed

The spatiotemporal behavior of the interaction between turbulence and flows has been studied close to the L-H transition threshold conditions in the edge region (??0.7) of TJ-II plasmas. The temporal dynamics of the interaction displays an oscillatory behavior with a characteristic predator-prey relationship. The spatial evolution of this turbulence-flow oscillation pattern has been measured, showing both radial outward and inward propagation velocities of the turbulence-flow front. The results indicate that the edge shear flow linked to the L-H transition can behave either as a slowing-down, damping mechanism of outward propagating turbulent-flow oscillating structures, or as a source of inward propagating turbulence-flow events. PMID:22243007

Estrada, T; Hidalgo, C; Happel, T; Diamond, P H

2011-12-07

291

Spatiotemporal Structure of the Interaction between Turbulence and Flows at the L-H Transition in a Toroidal Plasma  

NASA Astrophysics Data System (ADS)

The spatiotemporal behavior of the interaction between turbulence and flows has been studied close to the L-H transition threshold conditions in the edge region (??0.7) of TJ-II plasmas. The temporal dynamics of the interaction displays an oscillatory behavior with a characteristic predator-prey relationship. The spatial evolution of this turbulence-flow oscillation pattern has been measured, showing both radial outward and inward propagation velocities of the turbulence-flow front. The results indicate that the edge shear flow linked to the L-H transition can behave either as a slowing-down, damping mechanism of outward propagating turbulent-flow oscillating structures, or as a source of inward propagating turbulence-flow events.

Estrada, T.; Hidalgo, C.; Happel, T.; Diamond, P. H.

2011-12-01

292

Population structure of a predatory beetle: the importance of gene flow for intertrophic level interactions.  

PubMed

Migration and gene flow of natural enemies play an important role in the stability of predator-prey interactions and community organization in both natural and managed systems. Yet, relative to that of their herbivorous insect prey, the genetic structure of natural enemy populations has been little studied. We present evidence that populations of the predatory coccinellid beetle Coleomegilla maculata (Coleoptera: Coccinellidae), are not genetically subdivided and that levels of gene flow among these populations are extremely high. Furthermore, in the same geographical area, gene flow of C. maculata was significantly (one order of magnitude) greater than that of an abundant prey species, the Colorado potato beetle Leptinotarsa decemlineata (Coleoptera: Chrysomelidae). The high mobility of this natural enemy relative to the insect herbivores on which it feeds may contribute to its effectiveness as a biological control agent in agricultural systems. PMID:8188496

Coll, M; Garcia de Mendoza, L; Roderick, G K

1994-03-01

293

The regulation of arbuscular mycorrhizal symbiosis by phosphate in pea involves early and systemic signalling events  

PubMed Central

Most plants form root symbioses with arbuscular mycorrhizal (AM) fungi, which provide them with phosphate and other nutrients. High soil phosphate levels are known to affect AM symbiosis negatively, but the underlying mechanisms are not understood. This report describes experimental conditions which triggered a novel mycorrhizal phenotype under high phosphate supply: the interaction between pea and two different AM fungi was almost completely abolished at a very early stage, prior to the formation of hyphopodia. As demonstrated by split-root experiments, down-regulation of AM symbiosis occurred at least partly in response to plant-derived signals. Early signalling events were examined with a focus on strigolactones, compounds which stimulate pre-symbiotic fungal growth and metabolism. Strigolactones were also recently identified as novel plant hormones contributing to the control of shoot branching. Root exudates of plants grown under high phosphate lost their ability to stimulate AM fungi and lacked strigolactones. In addition, a systemic down-regulation of strigolactone release by high phosphate supply was demonstrated using split-root systems. Nevertheless, supplementation with exogenous strigolactones failed to restore root colonization under high phosphate. This observation does not exclude a contribution of strigolactones to the regulation of AM symbiosis by phosphate, but indicates that they are not the only factor involved. Together, the results suggest the existence of additional early signals that may control the differentiation of hyphopodia.

Balzergue, Coline; Puech-Pages, Virginie; Becard, Guillaume; Rochange, Soizic F.

2011-01-01

294

Hydrogen peroxide-regulated genes in the Medicago truncatula-Sinorhizobium meliloti symbiosis.  

PubMed

Reactive oxygen species (ROS), particularly hydrogen peroxide (H(2)O(2)), play an important role in signalling in various cellular processes. The involvement of H(2)O(2) in the Medicago truncatula-Sinorhizobium meliloti symbiotic interaction raises questions about its effect on gene expression. A transcriptome analysis was performed on inoculated roots of M. truncatula in which ROS production was inhibited with diphenylene iodonium (DPI). In total, 301 genes potentially regulated by ROS content were identified 2 d after inoculation. These genes included MtSpk1, which encodes a putative protein kinase and is induced by exogenous H(2)O(2) treatment. MtSpk1 gene expression was also induced by nodulation factor treatment. MtSpk1 transcription was observed in infected root hair cells, nodule primordia and the infection zone of mature nodules. Analysis with a fluorescent protein probe specific for H(2)O(2) showed that MtSpk1 expression and H(2)O(2) were similarly distributed in the nodule infection zone. Finally, the establishment of symbiosis was impaired by MtSpk1 downregulation with an artificial micro-RNA. Several genes regulated by H(2)O(2) during the establishment of rhizobial symbiosis were identified. The involvement of MtSpk1 in the establishment of the symbiosis is proposed. PMID:23347006

Andrio, Emilie; Marino, Daniel; Marmeys, Anthony; de Segonzac, Marion Dunoyer; Damiani, Isabelle; Genre, Andrea; Huguet, Stéphanie; Frendo, Pierre; Puppo, Alain; Pauly, Nicolas

2013-01-24

295

Arbuscular mycorrhizal symbiosis influences strigolactone production under salinity and alleviates salt stress in lettuce plants.  

PubMed

Arbuscular mycorrhizal (AM) symbiosis can alleviate salt stress in plants. However the intimate mechanisms involved, as well as the effect of salinity on the production of signalling molecules associated to the host plant-AM fungus interaction remains largely unknown. In the present work, we have investigated the effects of salinity on lettuce plant performance and production of strigolactones, and assessed its influence on mycorrhizal root colonization. Three different salt concentrations were applied to mycorrhizal and non-mycorrhizal plants, and their effects, over time, analyzed. Plant biomass, stomatal conductance, efficiency of photosystem II, as well as ABA content and strigolactone production were assessed. The expression of ABA biosynthesis genes was also analyzed. AM plants showed improved growth rates and a better performance of physiological parameters such as stomatal conductance and efficiency of photosystem II than non-mycorrhizal plants under salt stress since very early stages - 3 weeks - of plant colonization. Moreover, ABA levels were lower in those plants, suggesting that they were less stressed than non-colonized plants. On the other hand, we show that both AM symbiosis and salinity influence strigolactone production, although in a different way in AM and non-AM plants. The results suggest that AM symbiosis alleviates salt stress by altering the hormonal profiles and affecting plant physiology in the host plant. Moreover, a correlation between strigolactone production, ABA content, AM root colonization and salinity level is shown. We propose here that under these unfavourable conditions, plants increase strigolactone production in order to promote symbiosis establishment to cope with salt stress. PMID:23102876

Aroca, Ricardo; Ruiz-Lozano, Juan Manuel; Zamarreño, Angel María; Paz, José Antonio; García-Mina, José María; Pozo, María José; López-Ráez, Juan Antonio

2012-10-23

296

The Genome of Laccaria Bi color Provides Insights into Mycorrhizal Symbiosis  

SciTech Connect

Mycorrhizal symbioses the union of roots and soil fungi are universal in terrestrial ecosystems and may have been fundamental to land colonization by plants1,2. Boreal, temperate and montane forests all depend on ectomycorrhizae1. Identification of the primary factors that regulate symbiotic development and metabolic activity will therefore open the door to understanding the role of ectomycorrhizae in plant development and physiology, allowing the full ecological significance of this symbiosis to be explored. Here we report the genome sequence of the ectomycorrhizal basidiomycete Laccaria bicolor (Fig. 1) and highlight gene sets involved in rhizosphere colonization and symbiosis. This 65-megabase genome assembly contains 20,000 predicted protein-encoding genes and a very large number of transposons and repeated sequences. We detected unexpected genomic features, most notably a battery of effector-type small secreted proteins (SSPs) with unknown function, several of which are only expressed in symbiotic tissues. The most highly expressed SSP accumulates in the proliferating hyphae colonizing the host root. The ectomycorrhizae-specific SSPs probably have a decisive role in the establishment of the symbiosis. The unexpected observation that the genome of L. bicolor lacks carbohydrate-active enzymes involved in degradation of plant cell walls, but maintains the ability to degrade non-plant cell wall polysaccharides, reveals the dual saprotrophic and biotrophic lifestyle of the mycorrhizal fungus that enables it to grow within both soil and living plant roots. The predicted gene inventory of the L. bicolor genome, therefore, points to previously unknown mechanisms of symbiosis operating in biotrophic mycorrhizal fungi. The availability of this genome provides an unparalleled opportunity to develop a deeper understanding of the processes by which symbionts interact with plants within their ecosystem to perform vital functions in the carbon and nitrogen cycles that are fundamental to sustainable plant productivity.

Martin, F [UMR, France; Aerts, A. [U.S. Department of Energy, Joint Genome Institute; Ahren, D [Lund University, Sweden; Brun, A [UMR, France; Duchaussoy, F [UMR, France; Gibon, J [UMR, France; Kohler, A [UMR, France; Lindquist, E [U.S. Department of Energy, Joint Genome Institute; Pereda, V [UMR, France; Salamov, A. [U.S. Department of Energy, Joint Genome Institute; Shapiro, HJ [U.S. Department of Energy, Joint Genome Institute; Wuyts, J [UMR, France; Blaudez, D [UMR, France; Buee, M [UMR, France; Brokstein, P [U.S. Department of Energy, Joint Genome Institute; Canbeck, B [Lund University, Sweden; Cohen, D [UMR, France; Courty, PE [UMR, France; Coutinho, PM [Architecture et Fonction des Macromolecules Biologiques, UMR 6098 CNRS and Unive; Danchin, E [Architecture et Fonction des Macromolecules Biologiques, UMR 6098 CNRS and Unive; Delaruelle, C [UMR, France; Detter, J C [U.S. Department of Energy, Joint Genome Institute; Deveau, A [UMR, France; DiFazio, Stephen P [West Virginia University; Duplessis, S [UMR, France; Fraissinet-Tachet, L [Universite de Lyon, France; Lucic, E [UMR, France; Frey-Klett, P [UMR, France; Fourrey, C [UMR, France; Feussner, I [Georg-August Universitat Gottingen Germany; Gay, G [Universite de Lyon, France; Grimwood, Jane [Stanford University; Hoegger, P J [Georg-August Universitat Gottingen Germany; Jain, P [University of Alabama, Huntsville; Kilaru, S [Georg-August Universitat Gottingen Germany; Labbe, J [UMR, France; Lin, Y C [Ghent University, Belgium; Legue, V [UMR, France; Le Tacon, F [UMR, France; Marmeisse, R [Universite de Lyon, France; Melayah, D [Universite de Lyon, France; Montanini, B [UMR, France; Muratet, M [University of Alabama, Huntsville; Nehls, U [Eberhard-Karls-Universitat, Tubingen, Germany; Niculita-Hirzel, H [University of Lausanne, Switzerland; Oudot-Le Secq, M P [UMR, France; Peter, M [UMR, France; Quesneville, H [Unite de Recherches en Genomique-Info,Evry Cedex; Rajashekar, B [Lund University, Sweden; Reich, M [UMR, France; Rouhler, N [UMR, France; Schmutz, Jeremy [Stanford University; Yin, Tongming [ORNL; Chalot, M [UMR, France; Henrissat, B [Architecture et Fonction des Macromolecules Biologiques, UMR 6098 CNRS and Unive; Kues, U [Georg-August Universitat Gottingen Germany; Lucas, S [U.S. Department of Energy, Joint Genome Institute; Van de Peer, Y [Ghent University, Belgium; Podila, G [University of Alabama, Huntsville; Polle, A [Georg-August Universitat Gottingen Germany; Pukkila, P J [University of North Carolina, Chapel Hill; Richardson, P M [U.S. Department of Energy, Joint Genome Institute; Rouze, P [Ghent University, Belgium; Sanders, I R [University of Lausanne, Switzerland; Stajich, J E [University of California, Berkeley; Tunlid, A [Lund University, Sweden; Tuskan, Gerald A [ORNL; Grigoriev, I. [U.S. Department of Energy, Joint Genome Institute

2008-01-01

297

Analogue Simulation in the Teaching of Population Ecology  

ERIC Educational Resources Information Center

|Described is the use of analogue computer modules in simulating population ecology. Computer modules demonstrating exponential growth and predator-prey interactions are described and diagramed. (SL)|

Summers, M. K.; Summers, J. M.

1976-01-01

298

Arbuscular mycorrhizal symbiosis and plant aquaporin expression.  

PubMed

Almost all land plants have developed a symbiosis with arbuscular mycorrhizal fungi. Establishment of the association is accompanied by structural changes in the plant root. During arbuscule formation fungal hyphae penetrate the root apoplast and install highly specialized interfaces for solute transport between plant and fungus. The periarbuscular membrane which is part of the plant plasma membrane surrounding arbuscular structures was shown to harbour a high density of different transport systems. Among these also expression of aquaporins was described, which potentially can act as a low affinity transport system for ammonia or ammonium. The present study provides data for expression, localization and function of plant aquaporins in the periarbuscular membrane of mycorrhizal Medicago truncatula plants. PMID:17109903

Uehlein, Norbert; Fileschi, Kerstin; Eckert, Martin; Bienert, Gerd Patrick; Bertl, Adam; Kaldenhoff, Ralf

2006-11-15

299

The fine line between mutualism and parasitism: complex effects in a cleaning symbiosis demonstrated by multiple field experiments.  

PubMed

Ecological theory and observational evidence suggest that symbiotic interactions such as cleaning symbioses can shift from mutualism to parasitism. However, field experimental evidence documenting these shifts has never been reported for a cleaning symbiosis. Here, we demonstrate shifts in a freshwater cleaning symbiosis in a system involving crayfish and branchiobdellid annelids. Branchiobdellids have been shown to benefit their hosts under some conditions by cleaning material from host crayfish's gill filaments. The system is uniquely suited as an experimental model for symbiosis due to ease of manipulation and ubiquity of the organisms. In three field experiments, we manipulated densities of worms on host crayfish and measured host growth in field enclosures. In all cases, the experiments revealed shifts from mutualism to parasitism: host crayfish growth was highest at intermediate densities of branchiobdellid symbionts, while high symbiont densities led to growth that was lower or not significantly different from 0-worm controls. Growth responses were consistent even though the three experiments involved different crayfish and worm species and were performed at different locations. Results also closely conformed to a previous laboratory experiment using the same system. The mechanism for these shifts appears to be that branchiobdellids switched from cleaning host gills at intermediate densities of worms to consuming host gill tissue at high densities. These outcomes clearly demonstrate shifts along a symbiosis continuum with the maximum benefits to the host at intermediate symbiont densities. At high symbiont densities, benefits to the host disappear, and there is some evidence for a weak parasitism. These are the first field experimental results to demonstrate such shifts in a cleaning symbiosis. PMID:22349861

Brown, Bryan L; Creed, Robert P; Skelton, James; Rollins, Mark A; Farrell, Kaitlin J

2012-02-19

300

OakContigDF159.1, a reference library for studying differential gene expression in Quercus robur during controlled biotic interactions: use for quantitative transcriptomic profiling of oak roots in ectomycorrhizal symbiosis.  

PubMed

Oaks (Quercus spp.), which are major forest trees in the northern hemisphere, host many biotic interactions, but molecular investigation of these interactions is limited by fragmentary genome data. To date, only 75 oak expressed sequence tags (ESTs) have been characterized in ectomycorrhizal (EM) symbioses. We synthesized seven beneficial and detrimental biotic interactions between microorganisms and animals and a clone (DF159) of Quercus robur. Sixteen 454 and eight Illumina cDNA libraries from leaves and roots were prepared and merged to establish a reference for RNA-Seq transcriptomic analysis of oak EMs with Piloderma croceum. Using the Mimicking Intelligent Read Assembly (MIRA) and Trinity assembler, the OakContigDF159.1 hybrid assembly, containing 65 712 contigs with a mean length of 1003 bp, was constructed, giving broad coverage of metabolic pathways. This allowed us to identify 3018 oak contigs that were differentially expressed in EMs, with genes encoding proline-rich cell wall proteins and ethylene signalling-related transcription factors showing up-regulation while auxin and defence-related genes were down-regulated. In addition to the first report of remorin expression in EMs, the extensive coverage provided by the study permitted detection of differential regulation within large gene families (nitrogen, phosphorus and sugar transporters, aquaporins). This might indicate specific mechanisms of genome regulation in oak EMs compared with other trees. PMID:23672230

Tarkka, Mika T; Herrmann, Sylvie; Wubet, Tesfaye; Feldhahn, Lasse; Recht, Sabine; Kurth, Florence; Mailänder, Sarah; Bönn, Markus; Neef, Maren; Angay, Oguzhan; Bacht, Michael; Graf, Marcel; Maboreke, Hazel; Fleischmann, Frank; Grams, Thorsten E E; Ruess, Liliane; Schädler, Martin; Brandl, Roland; Scheu, Stefan; Schrey, Silvia D; Grosse, Ivo; Buscot, François

2013-05-15

301

Shared skeletal support in a coral-hydroid symbiosis.  

PubMed

Hydroids form symbiotic relationships with a range of invertebrate hosts. Where they live with colonial invertebrates such as corals or bryozoans the hydroids may benefit from the physical support and protection of their host's hard exoskeleton, but how they interact with them is unknown. Electron microscopy was used to investigate the physical interactions between the colonial hydroid Zanclea margaritae and its reef-building coral host Acropora muricata. The hydroid tissues extend below the coral tissue surface sitting in direct contact with the host's skeleton. Although this arrangement provides the hydroid with protective support, it also presents problems of potential interference with the coral's growth processes and exposes the hydroid to overgrowth and smothering. Desmocytes located within the epidermal layer of the hydroid's perisarc-free hydrorhizae fasten it to the coral skeleton. The large apical surface area of the desmocyte and high bifurcation of the distal end within the mesoglea, as well as the clustering of desmocytes suggests that a very strong attachment between the hydroid and the coral skeleton. This is the first study to provide a detailed description of how symbiotic hydroids attach to their host's skeleton, utilising it for physical support. Results suggest that the loss of perisarc, a characteristic commonly associated with symbiosis, allows the hydroid to utilise desmocytes for attachment. The use of these anchoring structures provides a dynamic method of attachment, facilitating detachment from the coral skeleton during extension, thereby avoiding overgrowth and smothering enabling the hydroid to remain within the host colony for prolonged periods of time. PMID:21695083

Pantos, Olga; Hoegh-Guldberg, Ove

2011-06-14

302

Symbiosis-enhanced gene expression in cnidarian-algal associations: cloning and characterization of a cDNA, sym32, encoding a possible cell adhesion protein  

Microsoft Academic Search

Mutualistic endosymbioses between two partners are complex associations that are regulated by the genetic interactions of the partners. One important marine symbiosis is that between various cnidarians, such as corals and anemones, and their photosynthetic algal symbionts. We have been interested in characterizing cnidarian host genes that are expressed as a function of the symbiotic state, using the temperate sea

W. S. Reynolds; J. A. Schwarz; V. M. Weis

2000-01-01

303

The nested structure of marine cleaning symbiosis: is it like flowers and bees?  

PubMed

In a given area, plant-animal mutualistic interactions form complex networks that often display nestedness, a particular type of asymmetry in interactions. Simple ecological and evolutionary factors have been hypothesized to lead to nested networks. Therefore, nestedness is expected to occur in other types of mutualisms as well. We tested the above prediction with the network structure of interactions in cleaning symbiosis at three reef assemblages. In this type of interaction, shrimps and fishes forage on ectoparasites and injured tissues from the body surface of fish species. Cleaning networks show strong patterns of nestedness. In fact, after controlling for species richness, cleaning networks are even more nested than plant-animal mutualisms. Our results support the notion that mutualisms evolve to a predictable community-level structure, be it in terrestrial or marine communities. PMID:17443964

Guimarães, Paulo R; Sazima, Cristina; dos Reis, Sérgio Furtado; Sazima, Ivan

2007-02-22

304

Social interactions, predation behaviour and fast start performance are affected by ammonia exposure in brown trout (Salmo trutta L.).  

PubMed

In fish, fast starts are brief, sudden accelerations during predator-prey encounters. They serve for escape and predation and are therefore ecologically important movements. Fast starts are generated by glycolytic muscle performance and are influenced by many internal and external factors. It is known that ammonia pollution has a major effect on the glycolytic muscle action, thus creating conditions in which fast start performance might be reduced and predation rates altered. Therefore, escape response and predation strikes were investigated in brown trout (Salmo trutta) of 10 and 20 cm body length exposed to an elevated (1 mg l(-1)) ammonia concentration for 24 and 96 h. Various locomotor and behavioural variables were measured. In C-starts, i.e. an escape start where the fish bends into a C-shaped position, ammonia exposure had no effect on response latency. After 96 h of exposure, cumulative distance, maximum swimming speed and turning radius of the prey were all significantly reduced and the escape went in no definite direction. The effect of ammonia exposure was more pronounced in large fish than in small fish. Predation strikes were also affected. Distance, speed and turning radius were significantly lower in exposed fish. Agonistic behaviour of dominant fish was significantly reduced and fish spent more time resting. Predator behaviour was also altered and the number of prey captured was reduced. This study shows that ammonia exposure affects brown trout escape response mainly through a reduction in fast start velocity and through an impairment of directionality. Thus, in addition to a reduced strength of the response, ammonia exposure could also reduce the fish's elusiveness facing a predator. Predation rate and social interactions are disrupted and predator-prey relationships could be altered. PMID:18829121

Tudorache, Christian; Blust, R; De Boeck, G

2008-08-27

305

Suppression of plant defence in rhizobia-legume symbiosis.  

PubMed

The symbiosis between rhizobia and legumes is characterized by the formation of dinitrogen-fixing root nodules. Although rhizobia colonize roots in a way that is reminiscent of pathogenic microorganisms, no host plant defence reactions are triggered during successful symbioses. Nevertheless, the plants obviously control the invading bacteria; failure in effective nodule formation or infections with rhizobia defective in surface polysaccharides often result in pathogenic responses. This article focuses on whether and how defence responses in effective symbiosis might be suppressed. Recent results suggest a central role for rhizobial polysaccharides acting as antagonists in the negative regulation of defence induction. PMID:12399178

Mithöfer, Axel

2002-10-01

306

Host–Bacterial Symbiosis in Health and Disease  

Microsoft Academic Search

All animals live in symbiosis. Shaped by eons of co-evolution, host-bacterial associations have developed into prosperous relationships creating mechanisms for mutual benefits to both microbe and host. No better example exists in biology than the astounding numbers of bacteria harbored by the lower gastrointestinal tract of mammals. The mammalian gut represents a complex ecosystem consisting of an extraordinary number of

Janet Chow; S. Melanie Lee; Yue Shen; Arya Khosravi; Sarkis K. Mazmanian

2010-01-01

307

Quorum sensing in the squid-Vibrio symbiosis.  

PubMed

Quorum sensing is an intercellular form of communication that bacteria use to coordinate group behaviors such as biofilm formation and the production of antibiotics and virulence factors. The term quorum sensing was originally coined to describe the mechanism underlying the onset of luminescence production in cultures of the marine bacterium Vibrio fischeri. Luminescence and, more generally, quorum sensing are important for V. fischeri to form a mutualistic symbiosis with the Hawaiian bobtail squid, Euprymna scolopes. The symbiosis is established when V. fischeri cells migrate via flagella-based motility from the surrounding seawater into a specialized structure injuvenile squid called the light organ. The cells grow to high cell densities within the light organ where the infection persists over the lifetime of the animal. A hallmark of a successful symbiosis is the luminescence produced by V. fischeri that camouflages the squid at night by eliminating its shadow within the water column. While the regulatory networks governing quorum sensing are critical for properly regulating V. fischeri luminescence within the squid light organ, they also regulate luminescence-independent processes during symbiosis. In this review, we discuss the quorum-sensing network of V. fischeri and highlight its impact at various stages during host colonization. PMID:23965960

Verma, Subhash C; Miyashiro, Tim

2013-08-07

308

Chapter 9: Symbiosis of plants, animals, and microbes  

Technology Transfer Automated Retrieval System (TEKTRAN)

A diversity of plants, animals and microbes on Earth abound due to evolution, climate, competition, and symbiosis. Single cell species such as microorganisms are assumed to have evolved initially. Over time, plants and animals established and flourished. As each new kingdom of life came about, the...

309

Methanotrophic marine molluscan (Bivalvia, Mytilidae) symbiosis: mussels fueled by gas  

Microsoft Academic Search

An undescribed mussel (family Mytilidae), which lives in the vicinity of hydrocarbon seeps in the Gulf of Mexico, consumes methane (the principal component of natural gas) at a high rate. The methane consumption is limited to the gills of these animals and is apparently due to the abundant intracellular bacteria found there. This demonstrates a methane-based symbiosis between an animal

J. J. Childress; C. R. Fisher; J. M. Brooks; M. C. II Kennicutt; R. Bidigare; A. E. Anderson

1986-01-01

310

Evaluation of Project Symbiosis: An Interdisciplinary Science Education Project.  

ERIC Educational Resources Information Center

|The goal of this report is to provide a summary of the evaluation of Project Symbiosis which focused on enhancing the teaching of science principles in high school agriculture courses. The project initially involved 15 teams of science and agriculture teachers and was characterized by an extensive evaluation component consisting of six formal…

Altschuld, James W.

1993-01-01

311

Reporters and Congressmen: Living in Symbiosis. Journalism Monographs No. 53.  

ERIC Educational Resources Information Center

|Although philosophers in the United States have advocated the concept of adversarity for the relationship between reporters and people in Congress, in actuality these two groups work together in symbiosis. This document reports on a study in which 190 reporters, members of Congress, and Congressional aides were interviewed regarding particular…

Miller, Susan Heilmann

312

A study of evolutionary multiagent models based on symbiosis  

Microsoft Academic Search

Multiagent Systems with Symbiotic Learning and Evolution (Masbiole) has been proposed and studied, which is a new methodology of Multiagent Systems (MAS) based on symbiosis in the ecosystem. Masbiole employs a method of symbiotic learning and evolution where agents can learn or evolve according to their symbiotic relations toward others, i.e., considering the benefits\\/losses of both itself and an opponent.

Toru Eguchi; Kotaro Hirasawa; Jinglu Hu; Nathan Ota

2006-01-01

313

Are biologists in 'future shock'? Symbiosis integrates biology across domains  

Microsoft Academic Search

The study of symbiosis is quintessential systems biology. It integrates not only all levels of biological analysis — from molecular to ecological — but also the study of the interplay between organisms in the three domains of life. The development of this field is still in its early stages, but so far, the findings promise to revolutionize the way we

Margaret McFall-Ngai

2008-01-01

314

Identification of genes controlling development of arbuscules in AM symbiosis  

Technology Transfer Automated Retrieval System (TEKTRAN)

Most vascular flowering plants have the capacity to form mutualistic symbioses with arbuscular mycorrhizal (AM) fungi. These associations develop in the roots where the fungus delivers phosphate to the root cortical cells and receives carbon from its plant host. During the symbiosis, the fungus prol...

315

The Mutual Symbiosis Between Inclusive Bilingual Education and Multicultural Education  

Microsoft Academic Search

In this article the authors postulate a mutual symbiosis between multicultural and inclusive bi-lingual education. Combining bi-lingual and multicultural education to create a symbiotic relationship can stimulate reform in schools and can promote inclusive educational systems, thereby keeping native languages and cultures alive for minority students and enhancing native English speakers’ language and cultural understandings.

Beverly J. Irby; Fuhui Tong

2011-01-01

316

Evolutionary innovation: a bone-eating marine symbiosis  

Microsoft Academic Search

Summary Symbiotic associations between microbes and inver- tebrates have resulted in some of the most unusual physiological and morphological adaptations that have evolved in the animal world. We document a new symbiosis between marine polychaetes of the genus Osedax and members of the bacterial group Oceano- spirillales, known for heterotrophic degradation of complex organic compounds. These organisms were discovered living

Shana K. Goffredi; Victoria J. Orphan; Greg W. Rouse; Linda Jahnke; Tsegeria Embaye; Kendra Turk; Ray Lee; Robert C. Vrijenhoek

2005-01-01

317

Microgravity effects on the legume\\/Rhizobium symbiosis  

Microsoft Academic Search

Symbiotic nitrogen fixation is of critical importance to world agriculture and likely will be a critical part of life support systems developed for prolonged missions in space. Bacteroid formation, an essential step in an effective Dutch White Clover\\/Rhizobium leguminosarum bv trifolii symbiosis, is induced by succinic acid which is produced by the plant and which is bound and incorporated by

James E. Urban

1997-01-01

318

Symbiosis-related pea genes modulate fungal and plant gene expression during the arbuscule stage of mycorrhiza with Glomus intraradices.  

PubMed

The arbuscular mycorrhiza association results from a successful interaction between genomes of the plant and fungal symbiotic partners. In this study, we analyzed the effect of inactivation of late-stage symbiosis-related pea genes on symbiosis-associated fungal and plant molecular responses in order to gain insight into their role in the functional mycorrhizal association. The expression of a subset of ten fungal and eight plant genes, previously reported to be activated during mycorrhiza development, was compared in Glomus intraradices-inoculated wild-type and isogenic genotypes of pea mutated for the PsSym36, PsSym33, and PsSym40 genes where arbuscule formation is inhibited or fungal turnover modulated, respectively. Microdissection was used to corroborate arbuscule-related fungal gene expression. Molecular responses varied between pea genotypes and with fungal development. Most of the fungal genes were downregulated when arbuscule formation was defective, and several were upregulated with more rapid fungal development. Some of the plant genes were also affected by inactivation of the PsSym36, PsSym33, and PsSym40 loci, but in a more time-dependent way during root colonization by G. intraradices. Results indicate a role of the late-stage symbiosis-related pea genes not only in mycorrhiza development but also in the symbiotic functioning of arbuscule-containing cells. PMID:20094894

Kuznetsova, Elena; Seddas-Dozolme, Pascale M A; Arnould, Christine; Tollot, Marie; van Tuinen, Diederik; Borisov, Alexey; Gianinazzi, Silvio; Gianinazzi-Pearson, Vivienne

2010-01-22

319

Symbiosis between methanogenic archaea and delta-proteobacteria as the origin of eukaryotes: the syntrophic hypothesis  

PubMed

We present a novel hypothesis for the origin of the eukaryotic cell, or eukaryogenesis, based on a metabolic symbiosis (syntrophy) between a methanogenic archaeon (methanobacterial-like) and a delta-proteobacterium (an ancestral sulfate-reducing myxobacterium). This syntrophic symbiosis was originally mediated by interspecies H2 transfer in anaerobic, possibly moderately thermophilic, environments. During eukaryogenesis, progressive cellular and genomic cointegration of both types of prokaryotic partners occurred. Initially, the establishment of permanent consortia, accompanied by extensive membrane development and close cell-cell interactions, led to a highly evolved symbiotic structure already endowed with some primitive eukaryotic features, such as a complex membrane system defining a protonuclear space (corresponding to the archaeal cytoplasm), and a protoplasmic region (derived from fusion of the surrounding bacterial cells). Simultaneously, bacterial-to-archaeal preferential gene transfer and eventual replacement took place. Bacterial genome extinction was thus accomplished by gradual transfer to the archaeal host, where genes adapted to a new genetic environment. Emerging eukaryotes would have inherited archaeal genome organization and dynamics and, consequently, most DNA-processing information systems. Conversely, primordial genes for social and developmental behavior would have been provided by the ancient myxobacterial symbiont. Metabolism would have been issued mainly from the versatile bacterial organotrophy, and progressively, methanogenesis was lost. PMID:9797402

Moreira; Lopez-Garcia

1998-11-01

320

Medicago truncatula Vapyrin is a novel protein required for arbuscular mycorrhizal symbiosis.  

PubMed

Arbuscular mycorrhizal (AM) symbiosis is a widespread mutualism formed between vascular plants and fungi of the Glomeromycota. In this endosymbiosis, fungal hyphae enter the roots, growing through epidermal cells to the cortex where they establish differentiated hyphae called arbuscules in the cortical cells. Reprogramming of the plant epidermal and cortical cells occurs to enable intracellular growth of the fungal symbiont; however, the plant genes underlying this process are largely unknown. Here, through the use of RNAi, we demonstrate that the expression of a Medicago truncatula gene named Vapyrin is essential for arbuscule formation, and also for efficient epidermal penetration by AM fungi. Vapyrin is induced transiently in the epidermis coincident with hyphal penetration, and then in the cortex during arbuscule formation. The Vapyrin protein is cytoplasmic, and in cells containing AM fungal hyphae, the protein accumulates in small puncta that move through the cytoplasm. Vapyrin is a novel protein composed of two domains that mediate protein-protein interactions: an N-terminal VAMP-associated protein (VAP)/major sperm protein (MSP) domain and a C-terminal ankyrin-repeat domain. Putative Vapyrin orthologs exist widely in the plant kingdom, but not in Arabidopsis, or in non-plant species. The data suggest a role for Vapyrin in cellular remodeling to support the intracellular development of fungal hyphae during AM symbiosis. PMID:19912567

Pumplin, Nathan; Mondo, Stephen J; Topp, Stephanie; Starker, Colby G; Gantt, J Stephen; Harrison, Maria J

2009-11-14

321

Expression of phenazine biosynthetic genes during the arbuscular mycorrhizal symbiosis of Glomus intraradices  

PubMed Central

To explore the molecular mechanisms that prevail during the establishment of the arbuscular mycorrhiza symbiosis involving the genus Glomus, we transcriptionally analysed spores of Glomus intraradices BE3 during early hyphal growth. Among 458 transcripts initially identified as being expressed at presymbiotic stages, 20% of sequences had homology to previously characterized eukaryotic genes, 30% were homologous to fungal coding sequences, and 9% showed homology to previously characterized bacterial genes. Among them, GintPbr1a encodes a homolog to Phenazine Biosynthesis Regulator (Pbr) of Burkholderia cenocepacia, an pleiotropic regulatory protein that activates phenazine production through transcriptional activation of the protein D isochorismatase biosynthetic enzyme phzD (Ramos et al., 2010). Whereas GintPbr1a is expressed during the presymbiotic phase, the G. intraradices BE3 homolog of phzD (BGintphzD) is transcriptionally active at the time of the establishment of the arbuscular mycorrhizal symbiosis. DNA from isolated bacterial cultures found in spores of G. intraradices BE3 confirmed that both BGintPbr1a and BGintphzD are present in the genome of its potential endosymbionts. Taken together, our results indicate that spores of G. intraradices BE3 express bacterial phenazine biosynthetic genes at the onset of the fungal-plant symbiotic interaction.

Leon-Martinez, Dionicia Gloria; Vielle-Calzada, Jean-Philippe; Olalde-Portugal, Victor

2012-01-01

322

Cellular mechanisms of Cnidarian bleaching: stress causes the collapse of symbiosis.  

PubMed

Cnidarian bleaching is a breakdown in the mutualistic symbiosis between host Cnidarians, such as reef building corals, and their unicellular photosynthetic dinoflagellate symbionts. Bleaching is caused by a variety of environmental stressors, most notably elevated temperatures associated with global climate change in conjunction with high solar radiation, and it is a major contributor to coral death and reef degradation. This review examines the underlying cellular events that lead to symbiosis dysfunction and cause bleaching, emphasizing that, to date, we have only some pieces of a complex cellular jigsaw puzzle. Reactive oxygen species (ROS), generated by damage to both photosynthetic and mitochondrial membranes, is shown to play a central role in both injury to the partners and to inter-partner communication of a stress response. Evidence is presented that suggests that bleaching is a host innate immune response to a compromised symbiont, much like innate immune responses in other host-microbe interactions. Finally, the elimination or exit of the symbiont from host tissues is described through a variety of mechanisms including exocytosis, host cell detachment and host cell apoptosis. PMID:18805804

Weis, Virginia M

2008-10-01

323

R gene-controlled host specificity in the legume-rhizobia symbiosis  

PubMed Central

Leguminous plants can enter into root nodule symbioses with nitrogen-fixing soil bacteria known as rhizobia. An intriguing but still poorly understood property of the symbiosis is its host specificity, which is controlled at multiple levels involving both rhizobial and host genes. It is widely believed that the host specificity is determined by specific recognition of bacterially derived Nod factors by the cognate host receptor(s). Here we describe the positional cloning of two soybean genes Rj2 and Rfg1 that restrict nodulation with specific strains of Bradyrhizobium japonicum and Sinorhizobium fredii, respectively. We show that Rj2 and Rfg1 are allelic genes encoding a member of the Toll-interleukin receptor/nucleotide-binding site/leucine-rich repeat (TIR-NBS-LRR) class of plant resistance (R) proteins. The involvement of host R genes in the control of genotype-specific infection and nodulation reveals a common recognition mechanism underlying symbiotic and pathogenic host–bacteria interactions and suggests the existence of their cognate avirulence genes derived from rhizobia. This study suggests that establishment of a root nodule symbiosis requires the evasion of plant immune responses triggered by rhizobial effectors.

Yang, Shengming; Tang, Fang; Gao, Muqiang; Krishnan, Hari B.; Zhu, Hongyan

2010-01-01

324

Sinister Symbiosis: Pathological Hematopoietic-Stromal Interactions in CML.  

PubMed

The impact of myeloid malignancies on the nonhematopoietic components of the bone marrow remains poorly understood. In this issue of Cell Stem Cell, Schepers et al. (2013) describe how malignant myeloid cells alter the endosteal hematopoietic stem cell (HSC) niche, resulting in the expansion of osteoblastic lineage cells that preferentially support malignant HSCs. PMID:24012363

Mullally, Ann; Ebert, Benjamin L

2013-09-01

325

Lotus japonicus E3 Ligase SEVEN IN ABSENTIA4 Destabilizes the Symbiosis Receptor-Like Kinase SYMRK and Negatively Regulates Rhizobial Infection[C][W  

PubMed Central

The Lotus japonicus SYMBIOSIS RECEPTOR-LIKE KINASE (SYMRK) is required for symbiotic signal transduction upon stimulation of root cells by microbial signaling molecules. Here, we identified members of the SEVEN IN ABSENTIA (SINA) E3 ubiquitin-ligase family as SYMRK interactors and confirmed their predicted ubiquitin-ligase activity. In Nicotiana benthamiana leaves, SYMRK–yellow fluorescent protein was localized at the plasma membrane, and interaction with SINAs, as determined by bimolecular fluorescence complementation, was observed in small punctae at the cytosolic interface of the plasma membrane. Moreover, fluorescence-tagged SINA4 partially colocalized with SYMRK and caused SYMRK relocalization as well as disappearance of SYMRK from the plasma membrane. Neither the localization nor the abundance of Nod-factor receptor1 was altered by the presence of SINA4. SINA4 was transcriptionally upregulated during root symbiosis, and rhizobia inoculated roots ectopically expressing SINA4 showed reduced SYMRK protein levels. In accordance with a negative regulatory role in symbiosis, infection thread development was impaired upon ectopic expression of SINA4. Our results implicate SINA4 E3 ubiquitin ligase in the turnover of SYMRK and provide a conceptual mechanism for its symbiosis-appropriate spatio-temporal containment.

Den Herder, Griet; Yoshida, Satoko; Antolin-Llovera, Meritxell; Ried, Martina K.; Parniske, Martin

2012-01-01

326

Realizing CO 2 emission reduction through industrial symbiosis: A cement production case study for Kawasaki  

Microsoft Academic Search

This article is one effort to examine the present and potential performances of CO2 emission reduction though industrial symbiosis by employing a case study approach and life cycle CO2 analysis for alternative industrial symbiosis scenarios. As one of the first and the best-known eco-town projects, Kawasaki Eco-town was chosen as a case study area. First, the current industrial symbiosis practices

Shizuka Hashimoto; Tsuyoshi Fujita; Yong Geng; Emiri Nagasawa

2010-01-01

327

Brain-Based Indices for User System Symbiosis  

Microsoft Academic Search

\\u000a The future generation user system interfaces need to be user-centric which goes beyond user-friendly and includes understanding\\u000a and anticipating user intentions. We introduce the concept of operator models, their role in implementing user-system symbiosis,\\u000a and the usefulness of brain-based indices on for instance effort, vigilance, workload and engagement to continuously update\\u000a the operator model. Currently, the best understood parameters in

Jan B. F. van Erp; Marc Grootjen

328

Endomycorrhizal and rhizobial symbiosis: How much do they share?  

Microsoft Academic Search

Legume plants enter two important endosymbioses – with soil fungi, forming phosphorus acquiring arbuscular mycorrhiza (AM), and with nitrogen-fixing bacteria, leading to the formation of nitrogen-fixing root nodules. Both symbioses have been studied extensively because these symbioses have great potential for agricultural applications. Although 80% of all living land plants form AM, the nitrogen-fixing root nodule symbiosis with rhizobia is

Geetanjali Manchanda; Neera Garg

2007-01-01

329

Symbiosis, lateral function transfer and the (many) saplings of life  

Microsoft Academic Search

One of intuitions driving the acceptance of a neat structured tree of life is the assumption that organisms and the lineages\\u000a they form have somewhat stable spatial and temporal boundaries. The phenomenon of symbiosis shows us that such ‘fixist’ assumptions\\u000a does not correspond to how the natural world actually works. The implications of lateral gene transfer (LGT) have been discussed

Frédéric Bouchard

2010-01-01

330

Microbial Biofilms: How Effective in Rhizobium –Legume Symbiosis?  

Microsoft Academic Search

\\u000a Diverse genera of bacteria live as microbial communities called biofilms on biotic or abiotic surfaces, or interfaces. They\\u000a exhibit elevated microbial action, as a result of symbiosis in biofilm structure and physiological adaptation. The formation\\u000a of fungal–bacterial biofilms by bacterial colonization on biotic fungal surfaces gives the biofilms enhanced microbial effectiveness\\u000a compared to monocultures. When the bacteria include rhizobia, they

G. Seneviratne; M. L. M. A. W. Weerasekara; J. S. Zavahir

331

Repeated loss of coloniality and symbiosis in scleractinian corals  

PubMed Central

The combination of coloniality and symbiosis in Scleractinia is thought to confer competitive advantage over other benthic invertebrates, and it is likely the key factor for the dominance of corals in tropical reefs. However, the extant Scleractinia are evenly split between zooxanthellate and azooxanthellate species. Most azooxanthellate species are solitary and nearly absent from reefs, but have much wider geographic and bathymetric distributions than reef corals. Molecular phylogenetic analyses have repeatedly recovered clades formed by colonial/zooxanthellate and solitary/azooxanthellate taxa, suggesting that coloniality and symbiosis were repeatedly acquired and/or lost throughout the history of the Scleractinia. Using Bayesian ancestral state reconstruction, we found that symbiosis was lost at least three times and coloniality lost at least six times, and at least two instances in which both characters were lost. All of the azooxanthellate lineages originated from ancestors that were reconstructed as symbiotic, corroborating the onshore–offshore diversification trend recorded in marine taxa. Symbiotic sister taxa of two of these descendant lineages are extant in Caribbean reefs but disappeared from the Mediterranean before the end of the Miocene, whereas extant azooxanthellate lineages have trans-Atlantic distributions. Thus, the phyletic link between reef and nonreef communities may have played an important role in the dynamics of extinction and recovery that marks the evolutionary history of scleractinians, and some reef lineages may have escaped local extinction by diversifying into offshore environments. However, this macroevolutionary mechanism offers no hope of mitigating the effects of climate change on coral reefs in the next century.

Barbeitos, Marcos S.; Romano, Sandra L.; Lasker, Howard R.

2010-01-01

332

Symbiosis through exploitation and the merger of lineages in evolution  

PubMed Central

A model for the coevolution of two species in facultative symbiosis is used to investigate conditions under which species merge to form a single reproductive unit. Two traits evolve in each species, the first affecting loss of resources from an individual to its partner, and the second affecting vertical transmission of the symbiosis from one generation to the next. Initial conditions are set so that the symbiosis involves exploitation of one partner by the other and vertical transmission is very rare. It is shown that, even in the face of continuing exploitation, a stable symbiotic unit can evolve with maximum vertical transmission of the partners. Such evolution requires that eventually deaths should exceed births for both species in the free-living state, a condition which can be met if the victim, in the course of developing its defences, builds up sufficiently large costs in the free-living state. This result expands the set of initial conditions from which separate lineages can be expected to merge into symbiotic units.

Law, R.; Dieckmann, U.

1998-01-01

333

Quantitative assessment of urban and industrial symbiosis in Kawasaki, Japan.  

PubMed

Colocated firms can achieve environmental benefit and competitive advantage from exchanging physical resources (known as industrial symbiosis) with each other or with residential areas (referenced here as urban symbiosis). Past research illustrated that economic and environmental benefits appear self-evident, although detailed quantification has only been attempted of symbioses for energy and water utilities. This article provides a complimentary case studyfor Kawasaki, Japan. The 14 documented symbioses connect steel, cement, chemical, and paperfirms and their spin-off recycling businesses. Seven key material exchanges divert annually at least 565 000 tons of waste from incineration or landfill. Four of these collectively present an estimated economic opportunity of 13.3 billion JPY (approximately 130 million USD) annually. Five symbioses involve utilization of byproduct and two sharing of utilities. The others are traditional or new recycling industries that do not specifically benefit from geographic proximity. The synergistic effect of urban and industrial symbiosis is unique. The legislative framework for a recycling-oriented society has contributed to realization of the symbioses, as has the availability of government subsidies through the Eco-Town program. PMID:19350890

Van Berkel, Rene; Fujita, Tsuyoshi; Hashimoto, Shizuka; Fujii, Minoru

2009-03-01

334

A Medicago truncatula phosphate transporter indispensable for the arbuscular mycorrhizal symbiosis  

PubMed Central

The arbuscular mycorrhizal (AM) symbiosis is a mutualistic endosymbiosis formed by plant roots and AM fungi. Most vascular flowering plants have the ability to form these associations, which have a significant impact on plant health and consequently on ecosystem function. Nutrient exchange is a central feature of the AM symbiosis, and AM fungi obtain carbon from their plant host while assisting the plant with the acquisition of phosphorus (as phosphate) from the soil. In the AM symbiosis, the fungus delivers Pi to the root through specialized hyphae called arbuscules. The molecular mechanisms of Pi and carbon transfer in the symbiosis are largely unknown, as are the mechanisms by which the plant regulates the symbiosis in response to its nutrient status. Plants possess many classes of Pi transport proteins, including a unique clade (Pht1, subfamily I), members of which are expressed only in the AM symbiosis. Here, we show that MtPT4, a Medicago truncatula member of subfamily I, is essential for the acquisition of Pi delivered by the AM fungus. However, more significantly, MtPT4 function is critical for AM symbiosis. Loss of MtPT4 function leads to premature death of the arbuscules; the fungus is unable to proliferate within the root, and symbiosis is terminated. Thus, Pi transport is not only a benefit for the plant but is also a requirement for the AM symbiosis.

Javot, Helene; Penmetsa, R. Varma; Terzaghi, Nadia; Cook, Douglas R.; Harrison, Maria J.

2007-01-01

335

Expression Islands Clustered on the Symbiosis Island of the Mesorhizobium loti Genome  

PubMed Central

Rhizobia are symbiotic nitrogen-fixing soil bacteria that are associated with host legumes. The establishment of rhizobial symbiosis requires signal exchanges between partners in microaerobic environments that result in mutualism for the two partners. We developed a macroarray for Mesorhizobium loti MAFF303099, a microsymbiont of the model legume Lotus japonicus, and monitored the transcriptional dynamics of the bacterium during symbiosis, microaerobiosis, and starvation. Global transcriptional profiling demonstrated that the clusters of genes within the symbiosis island (611 kb), a transmissible region distinct from other chromosomal regions, are collectively expressed during symbiosis, whereas genes outside the island are downregulated. This finding implies that the huge symbiosis island functions as clustered expression islands to support symbiotic nitrogen fixation. Interestingly, most transposase genes on the symbiosis island were highly upregulated in bacteroids, as were nif, fix, fdx, and rpoN. The genome region containing the fixNOPQ genes outside the symbiosis island was markedly upregulated as another expression island under both microaerobic and symbiotic conditions. The symbiosis profiling data suggested that there was activation of amino acid metabolism, as well as nif-fix gene expression. In contrast, genes for cell wall synthesis, cell division, DNA replication, and flagella were strongly repressed in differentiated bacteroids. A highly upregulated gene in bacteroids, mlr5932 (encoding 1-aminocyclopropane-1-carboxylate deaminase), was disrupted and was confirmed to be involved in nodulation enhancement, indicating that disruption of highly expressed genes is a useful strategy for exploring novel gene functions in symbiosis.

Uchiumi, Toshiki; Ohwada, Takuji; Itakura, Manabu; Mitsui, Hisayuki; Nukui, Noriyuki; Dawadi, Pramod; Kaneko, Takakazu; Tabata, Satoshi; Yokoyama, Tadashi; Tejima, Kouhei; Saeki, Kazuhiko; Omori, Hirofumi; Hayashi, Makoto; Maekawa, Takaki; Sriprang, Rutchadaporn; Murooka, Yoshikatsu; Tajima, Shigeyuki; Simomura, Kenshiro; Nomura, Mika; Suzuki, Akihiro; Shimoda, Yoshikazu; Sioya, Kouki; Abe, Mikiko; Minamisawa, Kiwamu

2004-01-01

336

The secret languages of coevolved symbioses: Insights from the Euprymna scolopes-Vibrio fischeri symbiosis  

PubMed Central

Recent research on a wide variety of systems has demonstrated that animals generally coevolve with their microbial symbionts. Although such relationships are most often established anew each generation, the partners associate with fidelity, i.e., they form exclusive alliances within the context of rich communities of non-symbiotic environmental microbes. The mechanisms by which this exclusivity is achieved and maintained remain largely unknown. Studies of the model symbiosis between the Hawaiian squid Euprymna scolopes and the marine luminous bacterium Vibrio fischeri provide evidence that the interplay between evolutionarily conserved features of the innate immune system, most notably MAMP/PRR interactions, and a specific feature of this association, i.e., luminescence, are critical for development and maintenance of this association. As such, in this partnership and perhaps others, symbiotic exclusivity is mediated by the synergism between a general animal-microbe ‘language’ and a ‘secret language’ that is decipherable only by the specific partners involved.

McFall-Ngai, Margaret; Heath-Heckman, Elizabeth A. C.; Gillette, Amani A.; Peyer, Suzanne M.; Harvie, Elizabeth A.

2011-01-01

337

Thiacloprid affects trophic interaction between gammarids and mayflies.  

PubMed

Neonicotinoid insecticides like thiacloprid enter agricultural surface waters, where they may affect predator-prey-interactions, which are of central importance for ecosystems as well as the functions these systems provide. The effects of field relevant thiacloprid concentrations on the leaf consumption of Gammarus fossarum (Amphipoda) were assessed over 96 h (n = 13-17) in conjunction with its predation on Baetis rhodani (Ephemeroptera) nymphs. The predation by Gammarus increased significantly at 0.50-1.00 ?g/L. Simultaneously, its leaf consumption decreased with increasing thiacloprid concentration. As a consequence of the increased predation at 1.00 ?g/L, gammarids' dry weight rose significantly by 15% compared to the control. At 4.00 ?g/L, the reduced leaf consumption was not compensated by an increase in predation causing a significantly reduced dry weight of Gammarus (?20%). These results may finally suggest that thiacloprid adversely affects trophic interactions, potentially translating into alterations in ecosystem functions, like leaf litter breakdown and aquatic-terrestrial subsidies. PMID:22522317

Englert, D; Bundschuh, M; Schulz, R

2012-04-21

338

Emergent properties of interacting populations of spiking neurons.  

PubMed

Dynamic neuronal networks are a key paradigm of increasing importance in brain research, concerned with the functional analysis of biological neuronal networks and, at the same time, with the synthesis of artificial brain-like systems. In this context, neuronal network models serve as mathematical tools to understand the function of brains, but they might as well develop into future tools for enhancing certain functions of our nervous system. Here, we present and discuss our recent achievements in developing multiplicative point processes into a viable mathematical framework for spiking network modeling. The perspective is that the dynamic behavior of these neuronal networks is faithfully reflected by a set of non-linear rate equations, describing all interactions on the population level. These equations are similar in structure to Lotka-Volterra equations, well known by their use in modeling predator-prey relations in population biology, but abundant applications to economic theory have also been described. We present a number of biologically relevant examples for spiking network function, which can be studied with the help of the aforementioned correspondence between spike trains and specific systems of non-linear coupled ordinary differential equations. We claim that, enabled by the use of multiplicative point processes, we can make essential contributions to a more thorough understanding of the dynamical properties of interacting neuronal populations. PMID:22207844

Cardanobile, Stefano; Rotter, Stefan

2011-12-23

339

Emergent Properties of Interacting Populations of Spiking Neurons  

PubMed Central

Dynamic neuronal networks are a key paradigm of increasing importance in brain research, concerned with the functional analysis of biological neuronal networks and, at the same time, with the synthesis of artificial brain-like systems. In this context, neuronal network models serve as mathematical tools to understand the function of brains, but they might as well develop into future tools for enhancing certain functions of our nervous system. Here, we present and discuss our recent achievements in developing multiplicative point processes into a viable mathematical framework for spiking network modeling. The perspective is that the dynamic behavior of these neuronal networks is faithfully reflected by a set of non-linear rate equations, describing all interactions on the population level. These equations are similar in structure to Lotka-Volterra equations, well known by their use in modeling predator-prey relations in population biology, but abundant applications to economic theory have also been described. We present a number of biologically relevant examples for spiking network function, which can be studied with the help of the aforementioned correspondence between spike trains and specific systems of non-linear coupled ordinary differential equations. We claim that, enabled by the use of multiplicative point processes, we can make essential contributions to a more thorough understanding of the dynamical properties of interacting neuronal populations.

Cardanobile, Stefano; Rotter, Stefan

2011-01-01

340

Functional diversity in coral-dinoflagellate symbiosis.  

PubMed

Symbioses are widespread in nature and occur along a continuum from parasitism to mutualism. Coral-dinoflagellate symbioses are defined as mutualistic because both partners receive benefit from the association via the exchange of nutrients. This successful interaction underpins the growth and formation of coral reefs. The symbiotic dinoflagellate genus Symbiodinium is genetically diverse containing eight divergent lineages (clades A-H). Corals predominantly associate with clade C Symbiodinium and to a lesser extent with clades A, B, D, F, and G. Variation in the function and interactive physiology of different coral-dinoflagellate assemblages is virtually unexplored but is an important consideration when developing the contextual framework of factors that contribute to coral reef resilience. In this study, we present evidence that clade A Symbiodinium are functionally less beneficial to corals than the dominant clade C Symbiodinium and may represent parasitic rather than mutualistic symbionts. Our hypothesis is supported by (i) a significant correlation between the presence of Symbiodinium clade A and health-compromised coral; (ii) a phylogeny and genetic diversity within Symbiodinium that suggests a different evolutionary trajectory for clade A compared with the other dominant Symbiodinium lineages; and (iii) a significantly lower amount of carbon fixed and released by clade A in the presence of a coral synthetic host factor as compared with the dominant coral symbiont lineage, clade C. Collectively, these data suggest that along the symbiotic continuum the interaction between clade A Symbiodinium and corals may be closer to parasitism than mutualism. PMID:18591663

Stat, Michael; Morris, Emily; Gates, Ruth D

2008-06-30

341

Functional diversity in coral-dinoflagellate symbiosis  

PubMed Central

Symbioses are widespread in nature and occur along a continuum from parasitism to mutualism. Coral–dinoflagellate symbioses are defined as mutualistic because both partners receive benefit from the association via the exchange of nutrients. This successful interaction underpins the growth and formation of coral reefs. The symbiotic dinoflagellate genus Symbiodinium is genetically diverse containing eight divergent lineages (clades A–H). Corals predominantly associate with clade C Symbiodinium and to a lesser extent with clades A, B, D, F, and G. Variation in the function and interactive physiology of different coral–dinoflagellate assemblages is virtually unexplored but is an important consideration when developing the contextual framework of factors that contribute to coral reef resilience. In this study, we present evidence that clade A Symbiodinium are functionally less beneficial to corals than the dominant clade C Symbiodinium and may represent parasitic rather than mutualistic symbionts. Our hypothesis is supported by (i) a significant correlation between the presence of Symbiodinium clade A and health-compromised coral; (ii) a phylogeny and genetic diversity within Symbiodinium that suggests a different evolutionary trajectory for clade A compared with the other dominant Symbiodinium lineages; and (iii) a significantly lower amount of carbon fixed and released by clade A in the presence of a coral synthetic host factor as compared with the dominant coral symbiont lineage, clade C. Collectively, these data suggest that along the symbiotic continuum the interaction between clade A Symbiodinium and corals may be closer to parasitism than mutualism.

Stat, Michael; Morris, Emily; Gates, Ruth D.

2008-01-01

342

Vapyrin, a gene essential for intracellular progression of arbuscular mycorrhizal symbiosis, is also essential for infection by rhizobia in the nodule symbiosis of Medicago truncatula.  

PubMed

Intracellular invasion of root cells is required for the establishment of successful endosymbioses in legumes of both arbuscular mycorrhizal (AM) fungi and rhizobial bacteria. In both interactions a requirement for successful entry is the activation of a common signalling pathway that includes five genes required to generate calcium oscillations and two genes required for the perception of the calcium response. Recently, it has been discovered that in Medicago truncatula, the Vapyrin (VPY) gene is essential for the establishment of the arbuscular mycorrhizal symbiosis. Here, we show by analyses of mutants that the same gene is also required for rhizobial colonization and nodulation. VPY encodes a protein featuring a Major Sperm Protein domain, typically featured on proteins involved in membrane trafficking and biogenesis, and a series of ankyrin repeats. Plants mutated in this gene have abnormal rhizobial infection threads and fewer nodules, and in the case of interactions with AM fungi, epidermal penetration defects and aborted arbuscule formation. Calcium spiking in root hairs in response to supplied Nod factors is intact in the vpy-1 mutant. This, and the elevation of VPY transcripts upon application of Nod factors which we show to be dependent on NFP, DMI1, and DMI3, indicates that VPY acts downstream of the common signalling pathway. PMID:21223389

Murray, Jeremy D; Muni, RajaSekhara Reddy Duvvuru; Torres-Jerez, Ivone; Tang, Yuhong; Allen, Stacy; Andriankaja, Megan; Li, Guangming; Laxmi, Ashverya; Cheng, Xiaofei; Wen, Jiangqi; Vaughan, David; Schultze, Michael; Sun, Jongho; Charpentier, Myriam; Oldroyd, Giles; Tadege, Million; Ratet, Pascal; Mysore, Kirankumar S; Chen, Rujin; Udvardi, Michael K

2010-11-29

343

Modeling Paleolithic Predator-Prey Dynamics and the Effects of Hunting Pressure on Prey ‘Choice’  

Microsoft Academic Search

Working from archaeofaunal trends in the Mediterranean Basin and modern wildlife data, we present a demographic interpretation\\u000a of Paleolithic prey “choice” with the aid of computer simulation modeling. Archaeological indications of expanding dietary\\u000a breadth with the onset of the Upper Paleolithic period associate with increasing exploitation of highly productive small animals\\u000a and smaller ungulate species, despite the higher procurement costs

Mary C. Stiner; Joseph E. Beaver; Natalie D. Munro; Todd A. Surovell

344

Predator-prey relationships within the pelagic community of Neusiedler See  

Microsoft Academic Search

Neusiedler See, a shallow alkaline lake, has become increasingly eutrophic; this enrichment improved the nutritive situation of the herbivorous zooplankton leading to a higher standing stock. A multiple regression analysis of the long-term development of the crustacean plankton indicates that abiotic factors (i.e. wind, temperature) have the most important impact on the community in spring and autumn, biotic factors (i.e.

Alois Herzig

1994-01-01

345

A jump-growth model for predator-prey dynamics: derivation and application to marine ecosystems.  

PubMed

This paper investigates the dynamics of biomass in a marine ecosystem. A stochastic process is defined in which organisms undergo jumps in body size as they catch and eat smaller organisms. Using a systematic expansion of the master equation, we derive a deterministic equation for the macroscopic dynamics, which we call the deterministic jump-growth equation, and a linear Fokker-Planck equation for the stochastic fluctuations. The McKendrick-von Foerster equation, used in previous studies, is shown to be a first-order approximation, appropriate in equilibrium systems where predators are much larger than their prey. The model has a power-law steady state consistent with the approximate constancy of mass density in logarithmic intervals of body mass often observed in marine ecosystems. The behaviours of the stochastic process, the deterministic jump-growth equation, and the McKendrick-von Foerster equation are compared using numerical methods. The numerical analysis shows two classes of attractors: steady states and travelling waves. PMID:20058090

Datta, Samik; Delius, Gustav W; Law, Richard

2010-01-08

346

Neutrophils in the War Against Staphylococcus aureus: Predator-Prey Models to the Rescue  

Microsoft Academic Search

To address the question of whether a minimum con- centration of blood neutrophils is necessary to decrease Staphylococcus aureus concentration in mastitic milk, literaturewassearchedforstudiesinwhichneutrophils were incubated with Staph. aureus. Different mathe- matical models that describe the changes in Staph. aureus population as a function of neutrophilic concen- trations were applied to the collected data. The best fitted model established (1)

J. C. Detilleux

2004-01-01

347

An introduction to repast simphony modeling using a simple predator-prey example  

Microsoft Academic Search

Repast is a widely used, free, and open-source, agent-based modeling and simulation toolkit. Three Repast platforms are currently available, each of which has the same core features but a different environment for these features. Repast Simphony (Repast S) extends the Repast portfolio by offering a new approach to simulation development and execution. This paper presents a model of wolf-sheep predation

E. Tatara; M. J. North; T. R. Howe; N. T. Collier; J. R. Vos; PantaRei Corp

2006-01-01

348

How Predator Food Preference can Change the Destiny of Native Prey in Predator–Prey Systems  

Microsoft Academic Search

The aim of this work is to develop and analyse a mathematical model for a predator-2 preys system arising in insular environments. We are interested in the evolution of a native prey population without behavioural traits to cope with predation or competition, after the introduction of alien species. Here, we consider a long living bird population with low fertility rate.

Sebastien Gaucel; Dominique Pontier

2005-01-01

349

A Predator-Prey Model for Moon-Triggered Clumping in Saturn's Rings  

NASA Astrophysics Data System (ADS)

UVIS occultation data show clumping in Saturn's F ring and at the B ring outer edge, indicating aggregation and disaggregation at these locations that are perturbed by Mimas and by Prometheus. Timescales range from hours to months. Structure near the B ring edge is seen in power spectral analysis at scales 200m - 2000m. We quantify this sub-km structure using wavelet analysis that estimates the statistical significance of the features. Similar structure is also seen at the strongest density waves, with significance increasing with resonance strength (FIGURE 1). For the B ring outer edge, the strongest structure is seen at longitudes 90° and 270° relative to Mimas. This indicates a direct relation between the moon and the ring clumping. We propose that the collective behavior of the ring particles resembles a predatorprey system: the mean aggregate size is the prey, which feeds the velocity dispersion; conversely, increasing dispersion breaks up the aggregates. Moons may trigger clumping by streamline crowding, which reduces the relative velocity, leading to more aggregation and more clumping. Disaggregation may follow from disruptive collisions or tidal shedding as the clumps stir the relative velocity. For realistic values of the parameters this yields a limit cycle behavior, as for the ecology of foxes and hares or the "boom-bust" economic cycle. Solving for the longterm behavior of this forced system gives a periodic response at the perturbing frequency, with a phase lag roughly consistent with the UVIS occultation measurements (FIGURE 2).

Esposito, L. W.; Albers, N.; Meinke, B. K.; Sremcevic, M.; Madhusudhanan, P.; Colwell, J. E.; Jerousek, R. E.

2011-10-01

350

Apes finding ants: Predator-prey dynamics in a chimpanzee habitat in Nigeria.  

PubMed

Some chimpanzee populations prey upon army ants, usually with stick tools. However, how their prey's subterranean nesting and nomadic lifestyle influence the apes' harvesting success is still poorly understood. This is particularly true for chimpanzees (Pan troglodytes ellioti) at Gashaka/Nigeria, which consume army ants (Dorylus rubellus) with much higher frequency than at other sites. We assessed various harvesting and search options theoretically available to the apes. For this, we reconstructed annual consumption patterns from feces and compared the physical characteristics of exploited ant nests with those that were not targeted. Repeated exploitation of a discovered nest is viable only in the short term, as disturbed colonies soon moved to a new site. Moreover, monitoring previously occupied nest cavities is uneconomical, as ants hardly ever re-used them. Thus, the apes have to detect new nests regularly, although colony density is relatively low (1 colony/1.3?ha). Surprisingly, visual search cues seem to be of limited importance because the probability of a nest being exploited was independent of its conspicuousness (presence of excavated soil piles, concealing leaf-litter or vegetation). However, chimpanzees preferentially targeted nests in forests or at the base of food trees, that is, where the apes spend relatively more time and/or where ant colony density is highest. Taken together, our findings suggest that, instead of employing a search strategy based on visual cues or spatial memory, chimpanzee predation on army ants contains a considerable opportunistic element. Am. J. Primatol. 75:1231-1244, 2013. © 2013 Wiley Periodicals, Inc. PMID:24022711

Pascual-Garrido, Alejandra; Umaru, Buba; Allon, Oliver; Sommer, Volker

2013-09-10

351

Predator-prey role reversals, juvenile experience and adult antipredator behaviour  

PubMed Central

Although biologists routinely label animals as predators and prey, the ecological role of individuals is often far from clear. There are many examples of role reversals in predators and prey, where adult prey attack vulnerable young predators. This implies that juvenile prey that escape from predation and become adult can kill juvenile predators. We show that such an exposure of juvenile prey to adult predators results in behavioural changes later in life: after becoming adult, these prey killed juvenile predators at a faster rate than prey that had not been exposed. The attacks were specifically aimed at predators of the species to which they had been exposed. This suggests that prey recognize the species of predator to which they were exposed during their juvenile stage. Our results show that juvenile experience affects adult behaviour after a role reversal.

Choh, Yasuyuki; Ignacio, Maira; Sabelis, Maurice W.; Janssen, Arne

2012-01-01

352

Sedentary snakes and gullible geckos: predator–prey coevolution in nocturnal rock-dwelling reptiles  

Microsoft Academic Search

We investigated (1) the importance of chemical cues for predator detection by the nocturnal, rock-dwelling velvet gecko,Oedura lesueurii, and (2) how the lizards’ responses to snake odour may have exerted selection on the foraging behaviours of a nocturnal elapid snake. This snake species (broadheaded snake,Hoplocephalus bungaroides) feeds primarily on velvet geckos, and does so by means of a distinctive foraging

SHARON DOWNES; RICHARD SHINE

1998-01-01

353

THE MOST POWERFUL TEST IN SOME CYCLIC PREDATOR-PREY POPULATIONS  

Microsoft Academic Search

In this article, we consider the Lotka-Volterra ordinary differential equations system (ODEs) where the actual population sizes are viewed as random perturbations of the solutions to the ODEs. Further, we assume that the perturbations follow correlated Ornstein-Uhlenbeck processes. For this model, we establish the most powerful test for testing change in the ODEs parameters.

Sévérien Nkurunziza; Sorana Froda; S. Ejaz Ahmed

2010-01-01

354

Evolution towards oscillation or stability in a predator-prey system  

PubMed Central

We studied a prey–predator system in which both species evolve. We discuss here the conditions that result in coevolution towards a stable equilibrium or towards oscillations. First, we show that a stable equilibrium or population oscillations with small amplitude is likely to occur if the prey's (host's) defence is effective when compared with the predator's (parasite's) attacking ability at equilibrium, whereas large-amplitude oscillations are likely if the predator's (parasite's) attacking ability exceeds the prey's (host's) defensive ability. Second, a stable equilibrium is more likely if the prey's defensive trait evolves faster than the predator's attack trait, whereas population oscillations are likely if the predator's trait evolves faster than that of the prey. Third, when the adaptation rates of both species are similar, the amplitude of the fluctuations in their abundances is small when the adaptation rate is either very slow or very fast, but at an intermediate rate of adaptation the fluctuations have a large amplitude. We also show the case in which the prey's abundance and trait fluctuate greatly, while those of the predator remain almost unchanged. Our results predict that populations and traits in host–parasite systems are more likely than those in prey–predator systems to show large-amplitude oscillations.

Mougi, Akihiko; Iwasa, Yoh

2010-01-01

355

Predator-prey oscillations, synchronization and pattern formation in ecological systems  

Microsoft Academic Search

Ecological systems and their component biological populations exhibit a broad spectrum of non-equilibrium dynamics ranging from characteristic natural cy-cles to more complex chaotic oscillations [1]. Perhaps the most spectacular example of this dynamic is Ecology's well known hare-lynx cycle. Despite unpredictable population fluctuations from one cycle to the next in the snow-shoe hare (Lepus americanus) and the Canadian lynx (Lynx

Bernd Blasius; Ralf Tonjes

356

Short Term Refuge Use and Stability of Predator-Prey Models  

Microsoft Academic Search

An individual-level behavioural model representing prey becoming temporarily less susceptible to attack in response to detection of predators is presented. This model is used to obtain a functional response for the predator which encapsulates a prey-hiding effect A density-dependent term is induced in the functional response which is structurally identical to that derived by Ruxton et al. (1992) using a

G. D. Ruxton

1995-01-01

357

Temperature-dependent predator-prey mite ecosystem on apple tree foliage  

Microsoft Academic Search

Summary  The biological control of the McDaniel spider mite, which is a pest on apple tree foliage, by a predacious mite species, which\\u000a feeds upon it, is represented by a continuous-discrete time hybrid model incorporating temperature effects explicityland mite\\u000a metamorphosis implicitly. The results of this model can be shown to provide good agreement when compared with relevant field\\u000a data.

D. J. Wollkind; J. A. Logan

1978-01-01

358

Predator-prey association in mono- and dicultures: Effect of maize and bean vegetation  

Microsoft Academic Search

The effect of bean and maize vegetation on the abundance of prey, predators, and predation rate in larvae of the Mexican bean beetle (Epilachna varivestis Mulsant (Coleoptera: Coccinellidae)) was investigated. Prey and predator densities were determined when bean and maize plants were grown alone (monocultures) and when bean plants were intercropped with tall or short maize plants (dicultures). On bean

Moshe Coll; Dale G. Bottrell

1995-01-01

359

The dynamics of a delayed predator-prey model with state dependent feedback control  

SciTech Connect

A delayed prey-predator model with state-dependent impulses is investigated. The sufficient conditions of existence and stability of semi-trivial solution and positive period-1 solution are obtained by using the Poincare map and analogue of the Poincare Criterion. The qualitative analysis shows that the positive period-one solution bifurcates from the semi-trivial solution through a fold bifurcation. The complex dynamics including chaos is obtained and numerical simulations substantiate the analytical results.

Singh, Anuraj; Gakkhar, Sunita [Department of Mathematics, Indian Institute of Technology Roorkee, Roorkee (India)

2011-11-30

360

Predator-prey coevolution: Australian native bees avoid their spider predators.  

PubMed Central

Australian crab spiders Thomisus spectabilis manipulate visual flower signals to lure introduced Apis mellifera. We gave Australian native bees, Austroplebia australis, the choice between two white daisies, Chrysanthemum frutescens, one of them occupied by a crab spider. The colour contrast between flowers and spiders affected the behaviour of native bees. Native bees approached spider-occupied flowers more frequently. However, native bees avoided flowers occupied by spiders and landed on vacant flowers more frequently. In contrast to honeybees that did not coevolve with T. spectabilis, Australian native bees show an anti-predatory response to avoid flowers occupied by this predator.

Heiling, A M; Herberstein, M E

2004-01-01

361

A Predator Prey Approach to Diversity Based Defenses in Heterogeneous Networks  

Microsoft Academic Search

In light of the rise of malicious attacks on the Internet, and the various networks and applications attached to it, new approaches towards modeling predatory activity in networks could be useful. Past research has simulated networks assuming that all vertices are homogenously susceptible to attack or infection. Often times in real world networks only subsets of vertices are susceptible to

Sean P. Gorman; Rajendra G. Kulkarni; Laurie A. Schintler; Roger R. Stough

2004-01-01

362

A Predator Prey Approach to Diversity Based Defenses in Heterogeneous Networks  

Microsoft Academic Search

In light of the rise of malicious attacks on the Internet, and the various\\u000anetworks and applications attached to it, new approaches towards modeling\\u000apredatory activity in networks could be useful. Past research has simulated\\u000anetworks assuming that all vertices are homogenously susceptible to attack or\\u000ainfection. Often times in real world networks only subsets of vertices are\\u000asusceptible to

Sean P. Gorman; Rajendra G. Kulkarni; Laurie A. Schintler; Roger R. Stough

2004-01-01

363

The symbiosis between Rhizobium leguminosarum and Pisum savitum: regulation of the nitrogenase activity  

Microsoft Academic Search

Bacteria of the genus Rhizobium can form a symbiosis with plants of the family Leguminosae. Both bacteria and plant show considerable biochemical and morphological changes in order to develop and carry out the symbiosis. The Rhizobia induce special structures on the legumes, which are called root nodules. In these root nodules, the differentiated bacteria - so-called bacteroids - are localized.

M. A. Appels

1989-01-01

364

LysM-Type Mycorrhizal Receptor Recruited for Rhizobium Symbiosis in Nonlegume Parasponia  

Microsoft Academic Search

Rhizobium-root nodule symbiosis is generally considered to be unique for legumes. However, there is one exception, and that is Parasponia. In this nonlegume, the rhizobial nodule symbiosis evolved independently and is, as in legumes, induced by rhizobium Nod factors. We used Parasponia andersonii to identify genetic constraints underlying evolution of Nod factor signaling. Part of the signaling cascade, downstream of

Rik Op den Camp; Arend Streng; Stéphane De Mita; Qingqin Cao; Elisa Polone; Wei Liu; Jetty S. S. Ammiraju; Dave Kudrna; Rod Wing; Andreas Untergasser; Ton Bisseling; René Geurts

2011-01-01

365

Carbon availability for the fungus triggers nitrogen uptake and transport in the arbuscular mycorrhizal symbiosis  

Technology Transfer Automated Retrieval System (TEKTRAN)

The arbuscular mycorrhizal (AM) symbiosis is characterized by a transfer of nutrients in exchange for carbon. We tested the effect of the carbon availability for the AM fungus Glomus intraradices on nitrogen (N) uptake and transport in the symbiosis. We followed the uptake and transport of 15N and ...

366

Symbiosis, Printspeak, and Politics: Topics in the Orality and Literacy Debate.  

ERIC Educational Resources Information Center

|Orality and literacy are not antithetical, rather they exist in a complex symbiosis at the individual, family, and community levels. Such a symbiosis is inevitable and appears in all kinds of institutions, including economic, political, social, cultural, and educatonal institutions. Out of this relationship, "printspeak" has emerged. Printspeak…

Bhola, H. S.

367

The nature of the symbiosis between Indo-Pacific anemone fishes and sea anemones  

Microsoft Academic Search

Under the general heading of symbiosis, defined originally to mean a “living together” of two dissimilar species, exist the sub-categories of mutualism (where both partners benefit), commensalism (where one partner benefits and the other is neutral) and parasitism (where one partner benefits and the other is harmed). The sea anemone-fish (mainly of the genus Amphiprion) symbiosis has generally been considered

R. N. Mariscal

1970-01-01

368

Vibrio fischeri metabolism: symbiosis and beyond.  

PubMed

Vibrio fischeri is a bioluminescent, Gram-negative marine bacterium that can be found free living and in a mutualistic association with certain squids and fishes. Over the past decades, the study of V. fischeri has led to important discoveries about bioluminescence, quorum sensing, and the mechanisms that underlie beneficial host-microbe interactions. This chapter highlights what has been learned about metabolic pathways in V. fischeri, and how this information contributes to a broader understanding of the role of bacterial metabolism in host colonization by both beneficial and pathogenic bacteria, as well as in the growth and survival of free-living bacteria. PMID:23046951

Dunn, Anne K

2012-01-01

369

Two putative-aquaporin genes are differentially expressed during arbuscular mycorrhizal symbiosis in Lotus japonicus  

PubMed Central

Background Arbuscular mycorrhizas (AM) are widespread symbioses that provide great advantages to the plant, improving its nutritional status and allowing the fungus to complete its life cycle. Nevertheless, molecular mechanisms that lead to the development of AM symbiosis are not yet fully deciphered. Here, we have focused on two putative aquaporin genes, LjNIP1 and LjXIP1, which resulted to be upregulated in a transcriptomic analysis performed on mycorrhizal roots of Lotus japonicus. Results A phylogenetic analysis has shown that the two putative aquaporins belong to different functional families: NIPs and XIPs. Transcriptomic experiments have shown the independence of their expression from their nutritional status but also a close correlation with mycorrhizal and rhizobial interaction. Further transcript quantification has revealed a good correlation between the expression of one of them, LjNIP1, and LjPT4, the phosphate transporter which is considered a marker gene for mycorrhizal functionality. By using laser microdissection, we have demonstrated that one of the two genes, LjNIP1, is expressed exclusively in arbuscule-containing cells. LjNIP1, in agreement with its putative role as an aquaporin, is capable of transferring water when expressed in yeast protoplasts. Confocal analysis have demonstrated that eGFP-LjNIP1, under its endogenous promoter, accumulates in the inner membrane system of arbusculated cells. Conclusions Overall, the results have shown different functionality and expression specificity of two mycorrhiza-inducible aquaporins in L. japonicus. One of them, LjNIP1 can be considered a novel molecular marker of mycorrhizal status at different developmental stages of the arbuscule. At the same time, LjXIP1 results to be the first XIP family aquaporin to be transcriptionally regulated during symbiosis.

2012-01-01

370

Stars and Symbiosis: MicroRNA- and MicroRNA*-Mediated Transcript Cleavage Involved in Arbuscular Mycorrhizal Symbiosis1[W][OA  

PubMed Central

The majority of plants are able to form the arbuscular mycorrhizal (AM) symbiosis in association with AM fungi. During symbiosis development, plant cells undergo a complex reprogramming resulting in profound morphological and physiological changes. MicroRNAs (miRNAs) are important components of the regulatory network of plant cells. To unravel the impact of miRNAs and miRNA-mediated mRNA cleavage on root cell reprogramming during AM symbiosis, we carried out high-throughput (Illumina) sequencing of small RNAs and degradome tags of Medicago truncatula roots. This led to the annotation of 243 novel miRNAs. An increased accumulation of several novel and conserved miRNAs in mycorrhizal roots suggest a role of these miRNAs during AM symbiosis. The degradome analysis led to the identification of 185 root transcripts as mature miRNA and also miRNA*-mediated mRNA cleavage targets. Several of the identified miRNA targets are known to be involved in root symbioses. In summary, the increased accumulation of specific miRNAs and the miRNA-mediated cleavage of symbiosis-relevant genes indicate that miRNAs are an important part of the regulatory network leading to symbiosis development.

Devers, Emanuel A.; Branscheid, Anja; May, Patrick; Krajinski, Franziska

2011-01-01

371

Interactions Between Benthic Predators and Zooplanktonic Prey are Affected by Turbulent Waves.  

PubMed

Predators capture prey in complex and variable environments. In the ocean, bottom-dwelling (benthic) organisms are subjected to water currents, waves, and turbulent eddies. For benthic predators that feed on small animals carried in the water (zooplankton), flow not only delivers prey, but can also shape predator-prey interactions. Benthic passive suspension feeders collect prey delivered by movement of ambient water onto capture-surfaces, whereas motile benthic predators, such as burrow-dwelling fish, dart out to catch passing zooplankton. How does the flow of ambient water affect these contrasting modes of predation by benthic zooplanktivores? We studied the effects of turbulent, wavy flow on the encounter, capture, and retention of motile zooplanktonic prey (copepods, Acartia spp.) by passive benthic suspension feeders (sea anemones, Anthopleura elegantissima). Predator-prey interactions were video-recorded in a wave-generating flume under two regimes of oscillating flow with different peak wave velocities and levels of turbulent kinetic energy ("weak" and "strong" waves). Rates of encounter (number of prey passing through a sea anemone's capture zone per time), capture (prey contacting and sticking to tentacles per time), and retention (prey retained on tentacles, without struggling free or washing off, per time) were measured at both strengths of waves. Strong waves enhanced encounter rates both for dead copepods and for actively swimming copepods, but there was so much variability in the behavior of the live prey that the effect of wave strength on encounter rates was not significant. Trapping efficiency (number of prey retained per number encountered) was the same in both flow regimes because, although fewer prey executed maneuvers to escape capture in strong waves, more of the captured prey was washed off the predators' tentacles. Although peak water velocities and turbulence of waves did not affect feeding rates of passive suspension-feeding sea anemones, increases in these aspects of flow have been shown to enhance feeding rates and efficiency of motile benthic fish that lunge out of their burrows to catch zooplankton. Faster, more turbulent flow interferes with the ability of prey to detect predators and execute escape maneuvers, and thus enhances capture rates both for passive suspension-feeding predators and for actively swimming predators. However, prey captured in the mouths of fish are not washed away by ambient flow, whereas prey captured on the tentacles of suspension feeders can be swept off before they are ingested. Therefore, the effects of flowing water on predation on zooplankton by benthic animals depend on the feeding mode of the predator. PMID:23942646

Robinson, H E; Finelli, C M; Koehl, M A R

2013-08-12

372

Methanotrophic marine molluscan (Bivalvia, Mytilidae) symbiosis: mussels fueled by gas  

SciTech Connect

An undescribed mussel (family Mytilidae), which lives in the vicinity of hydrocarbon seeps in the Gulf of Mexico, consumes methane (the principal component of natural gas) at a high rate. The methane consumption is limited to the gills of these animals and is apparently due to the abundant intracellular bacteria found there. This demonstrates a methane-based symbiosis between an animal and intracellular bacteria. Methane consumption is dependent on the availability of oxygen and is inhibited by acetylene. The consumption of methane by these mussels is associated with a dramatic increase in oxygen consumption and carbon dioxide production. As the methane consumption of the bivalve can exceed its carbide dioxide production, the symbiosis may be able to entirely satisfy its carbon needs from methane uptake. The very light (delta/sup 13/C = -51 to -57 per mil) stable carbon isotope ratios found in this animal support methane (delta/sup 13/C = -45 per mil at this site) as the primary carbon source for both the mussels and their symbionts. 19 references, 2 figures, 1 table.

Childress, J.J.; Fisher, C.R.; Brooks, J.M.; Kennicutt, M.C. II; Bidigare, R.; Anderson, A.E.

1986-09-19

373

Aphids evolved novel secreted proteins for symbiosis with bacterial endosymbiont.  

PubMed

Aphids evolved novel cells, called bacteriocytes, that differentiate specifically to harbour the obligatory mutualistic endosymbiotic bacteria Buchnera aphidicola. The genome of the host aphid Acyrthosiphon pisum contains many orphan genes that display no similarity with genes found in other sequenced organisms, prompting us to hypothesize that some of these orphan genes are related to lineage-specific traits, such as symbiosis. We conducted deep sequencing of bacteriocytes mRNA followed by whole mount in situ hybridizations of over-represented transcripts encoding aphid-specific orphan proteins. We identified a novel class of genes that encode small proteins with signal peptides, which are often cysteine-rich, that are over-represented in bacteriocytes. These genes are first expressed at a developmental time point coincident with the incorporation of symbionts strictly in the cells that contribute to the bacteriocyte and this bacteriocyte-specific expression is maintained throughout the aphid's life. The expression pattern suggests that recently evolved secretion proteins act within bacteriocytes, perhaps to mediate the symbiosis with beneficial bacterial partners, which is reminiscent of the evolution of novel cysteine-rich secreted proteins of leguminous plants that regulate nitrogen-fixing endosymbionts. PMID:23173201

Shigenobu, Shuji; Stern, David L

2013-01-01

374

Key Role of Bacterial NH4+ Metabolism in Rhizobium-Plant Symbiosis  

PubMed Central

Symbiotic nitrogen fixation is carried out in specialized organs, the nodules, whose formation is induced on leguminous host plants by bacteria belonging to the family Rhizobiaceae. Nodule development is a complex multistep process, which requires continued interaction between the two partners and thus the exchange of different signals and metabolites. NH4+ is not only the primary product but also the main regulator of the symbiosis: either as ammonium and after conversion into organic compounds, it regulates most stages of the interaction, from the production of nodule inducers to the growth, function, and maintenance of nodules. This review examines the adaptation of bacterial NH4+ metabolism to the variable environment generated by the plant, which actively controls and restricts bacterial growth by affecting oxygen and nutrient availability, thereby allowing a proficient interaction and at the same time preventing parasitic invasion. We describe the regulatory circuitry responsible for the downregulation of bacterial genes involved in NH4+ assimilation occurring early during nodule invasion. This is a key and necessary step for the differentiation of N2-fixing bacteroids (the endocellular symbiotic form of rhizobia) and for the development of efficient nodules.

Patriarca, Eduardo J.; Tate, Rosarita; Iaccarino, Maurizio

2002-01-01

375

Only One of Five groEL Genes Is Required for Viability and Successful Symbiosis in Sinorhizobium meliloti?  

PubMed Central

Many bacterial species contain multiple copies of the genes that encode the chaperone GroEL and its cochaperone, GroES, including all of the fully sequenced root-nodulating bacteria that interact symbiotically with legumes to generate fixed nitrogen. In particular, in Sinorhizobium meliloti there are four groESL operons and one groEL gene. To uncover functional redundancies of these genes during growth and symbiosis, we attempted to construct strains containing all combinations of groEL mutations. Although a double groEL1 groEL2 mutant cannot be constructed, we demonstrate that the quadruple groEL1 groESL3 groEL4 groESL5 and groEL2 groESL3 groEL4 groESL5 mutants are viable. Therefore, like E. coli and other species, S. meliloti requires only one groEL gene for viability, and either groEL1 or groEL2 will suffice. The groEL1 groESL5 double mutant is more severely affected for growth at both 30°C and 40°C than the single mutants, suggesting overlapping functions in stress response. During symbiosis the quadruple groEL2 groESL3 groEL4 groESL5 mutant acts like the wild type, but the quadruple groEL1 groESL3 groEL4 groESL5 mutant acts like the groEL1 single mutant, which cannot fully induce nod gene expression and forms ineffective nodules. Therefore, the only groEL gene required for symbiosis is groEL1. However, we show that the other groE genes are expressed in the nodule at lower levels, suggesting minor roles during symbiosis. Combining our data with other data, we conclude that groESL1 encodes the housekeeping GroEL/GroES chaperone and that groESL5 is specialized for stress response.

Bittner, Alycia N.; Foltz, Amanda; Oke, Valerie

2007-01-01

376

Unveiling in situ interactions between marine protists and bacteria through single cell sequencing  

PubMed Central

Heterotrophic protists are a highly diverse and biogeochemically significant component of marine ecosystems, yet little is known about their species-specific prey preferences and symbiotic interactions in situ. Here we demonstrate how these previously unresolved questions can be addressed by sequencing the eukaryote and bacterial SSU rRNA genes from individual, uncultured protist cells collected from their natural marine environment and sorted by flow cytometry. We detected Pelagibacter ubique in association with a MAST-4 protist, an actinobacterium in association with a chrysophyte and three bacteroidetes in association with diverse protist groups. The presence of identical phylotypes among the putative prey and the free bacterioplankton in the same sample provides evidence for predator–prey interactions. Our results also suggest a discovery of novel symbionts, distantly related to Rickettsiales and the candidate divisions ZB3 and TG2, associated with Cercozoa and Chrysophyta cells. This study demonstrates the power of single cell sequencing to untangle ecological interactions between uncultured protists and prokaryotes.

Martinez-Garcia, Manuel; Brazel, David; Poulton, Nicole J; Swan, Brandon K; Gomez, Monica Lluesma; Masland, Dashiell; Sieracki, Michael E; Stepanauskas, Ramunas

2012-01-01

377

Effects of multiple climate change factors on the tall fescue-fungal endophyte symbiosis: infection frequency and tissue chemistry.  

SciTech Connect

Climate change (altered CO{sub 2}, warming, and precipitation) may affect plant-microbial interactions, such as the Lolium arundinaceum-Neotyphodium coenophialum symbiosis, to alter future ecosystem structure and function. To assess this possibility, tall fescue tillers were collected from an existing climate manipulation experiment in a constructed old-field community in Tennessee (USA). Endophyte infection frequency (EIF) was determined, and infected (E+) and uninfected (E-) tillers were analysed for tissue chemistry. The EIF of tall fescue was higher under elevated CO{sub 2} (91% infected) than with ambient CO{sub 2} (81%) but was not affected by warming or precipitation treatments. Within E+ tillers, elevated CO{sub 2} decreased alkaloid concentrations of both ergovaline and loline, by c. 30%; whereas warming increased loline concentrations 28% but had no effect on ergovaline. Independent of endophyte infection, elevated CO{sub 2} reduced concentrations of nitrogen, cellulose, hemicellulose, and lignin. These results suggest that elevated CO{sub 2}, more than changes in temperature or precipitation, may promote this grass-fungal symbiosis, leading to higher EIF in tall fescue in old-field communities. However, as all three climate factors are likely to change in the future, predicting the symbiotic response and resulting ecological consequences may be difficult and dependent on the specific atmospheric and climatic conditions encountered.

Brosi, Glade [University of Kentucky; McCulley, Rebecca L [University of Kentucky; Bush, L P [University of Kentucky; Nelson, Jim A [University of Kentucky; Classen, Aimee T [University of Tennessee, Knoxville (UTK); Norby, Richard J [ORNL

2011-01-01

378

Combined phosphate and nitrogen limitation generates a nutrient stress transcriptome favorable for arbuscular mycorrhizal symbiosis in Medicago truncatula.  

PubMed

Arbuscular mycorrhizal (AM) symbiosis is stimulated by phosphorus (P) limitation and contributes to P and nitrogen (N) acquisition. However, the effects of combined P and N limitation on AM formation are largely unknown. Medicago truncatula plants were cultivated in the presence or absence of Rhizophagus irregularis (formerly Glomus intraradices) in P-limited (LP), N-limited (LN) or combined P- and N-limited (LPN) conditions, and compared with plants grown in sufficient P and N. The highest AM formation was observed in LPN, linked to systemic signaling by the plant nutrient status. Plant free phosphate concentrations were higher in LPN than in LP, as a result of cross-talk between P and N. Transcriptome analyses suggest that LPN induces the activation of NADPH oxidases in roots, concomitant with an altered profile of plant defense genes and a coordinate increase in the expression of genes involved in the methylerythritol phosphate and isoprenoid-derived pathways, including strigolactone synthesis genes. Taken together, these results suggest that low P and N fertilization systemically induces a physiological state of plants favorable for AM symbiosis despite their higher P status. Our findings highlight the importance of the plant nutrient status in controlling plant-fungus interaction. PMID:23506613

Bonneau, Laurent; Huguet, Stéphanie; Wipf, Daniel; Pauly, Nicolas; Truong, Hoai-Nam

2013-03-18

379

Fungal Symbiosis in Rice Requires an Ortholog of a Legume Common Symbiosis Gene Encoding a Ca2+/Calmodulin-Dependent Protein Kinase1[OA  

PubMed Central

In natural ecosystems, many plants are able to establish mutually beneficial symbioses with microorganisms. Of critical importance to sustainable agriculture are the symbioses formed between more than 80% of terrestrial plants and arbuscular mycorrhizal (AM) fungi and between legumes and nitrogen-fixing rhizobial bacteria. Interestingly, the two symbioses share overlapping signaling pathways in legumes, suggesting that the evolutionarily recent root nodule symbiosis may have acquired functions from the ancient AM symbiosis. The Medicago truncatula DMI3 (DOESN'T MAKE INFECTIONS3) gene (MtDMI3) and its orthologs in legumes are required for both bacterial and fungal symbioses. MtDMI3 encodes a Ca2+/calmodulin-dependent protein kinase (CCaMK) essential for the transduction of the Ca2+ signal induced by the perception of Nod factors. Putative orthologs of MtDMI3 are also present in non-legumes, but their function in AM symbiosis has not been demonstrated in any non-legume species. Here, we combine reverse genetic approaches and a cross-species complementation test to characterize the function of the rice (Oryza sativa) ortholog of MtDMI3, namely, OsDMI3, in AM symbiosis. We demonstrate that OsDMI3 is not only required for AM symbiosis in rice but also is able to complement a M. truncatula dmi3 mutant, indicating an equivalent role of MtDMI3 orthologs in non-legumes.

Chen, Caiyan; Gao, Muqiang; Liu, Jinyuan; Zhu, Hongyan

2007-01-01

380

Component modeling in ecological risk assessment: Disturbance in interspecific interactions caused by air toxics introduced into terrestrial ecosystems  

NASA Astrophysics Data System (ADS)

The human health risk assessment (HRA), initiated by the onset of nuclear industry, has been a well established methodology for assessing the impacts of human created contamination on an individual human being and entire population. The wide spread of applications and tools grown upon this methodology allows one not only to identify the hazards, but also to manage the risks. Recently, there has existed an increased awareness of the need to conduct ecological risk assessments (ERA) in addition to HRAs. The ERAs are, by and large, more complex than typical HRAs and involve not only different species but whole ecological systems. Such complex analyses require a thorough understanding of the processes underway in the ecosystem, including the contaminant transport through the food web, population dynamics as well as intra- and inter-specific relationships. The exposure pathways change radically depending on the consumer tier. Plants produce their nutriment from the sunlight and raw inorganic compounds. Animals and other living forms obtain energy by eating plants, other animals and detritus. Their double role as food consumers and food producers causes a trophic structure of the ecological system, where nutrients and energy are transferred from one trophic level to another. This is a dynamic process of energy flow, mostly in the form of food, varying with time and space. In order to conduct an efficient ERA, a multidisciplinary framework is needed. This framework can be enhanced by analyzing predator-prey interactions during the environmental disturbances caused by a pollutant emission, and by assessing the consequences of such disturbances. It is necessary to develop a way to describe how human industrial activity affects the ecosystems. Existing ecological studies have mostly been focused either on pure ecological interdependencies or on limited perspectives of human activities. In this study, we discuss the issues of air pollution and its ecological impacts from the Ecological Risk Assessment standpoint and examine the impact of air toxics emissions on an ecosystem, with particular emphasis on predator-prey interactions. Such analysis may help to identify the most likely conditions leading to the ecosystem instability and possibility of its recuperation.

Swider, Jan Zenon

381

Experimental exposure of juvenile snails ( Potamopyrgus antipodarum ?) to infection by trematode larvae ( Microphallus sp.): infectivity, fecundity compensation and growth  

Microsoft Academic Search

Host-parasite interactions that result in host castration are evolutionarily similar to predator-prey interactions because\\u000a both interactions terminate reproduction for the host or prey. Yet, host-parasite interactions differ from predator-prey interactions\\u000a in that infected hosts remain alive and potentially can make adjustments to their life-history strategy before castration\\u000a is complete. Here we exposed juvenile snails (Potamopyrgus antipodarum) to infection by a

Amy C. Krist; Curtis M. Lively

1998-01-01

382

50 CFR 600.310 - National Standard 1-Optimum Yield.  

Code of Federal Regulations, 2010 CFR

...forage fish stocks, other fisheries, predator-prey or competitive interactions, marine mammals, threatened or endangered species, and birds. Species interactions that have not been explicitly taken into account when calculating...

2010-10-01

383

50 CFR 600.310 - National Standard 1-Optimum Yield.  

Code of Federal Regulations, 2010 CFR

...forage fish stocks, other fisheries, predator-prey or competitive interactions, marine mammals, threatened or endangered species, and birds. Species interactions that have not been explicitly taken into account when calculating...

2009-10-01

384

Nuclear energy and waste management pyroprocess for system symbiosis  

NASA Astrophysics Data System (ADS)

The actinide management has become a key issue in nuclear energy. Recovering and fissioning transuranium elements reduce the long-term proliferation risks and the environmental burden. The better way of waste management will be made by system symbiosis: a combination of light-water reactor and fast reactor and/or accelerator-driven transmutation system should be sought. The new recycling technology should be able to achieve good economy with smaller plants, which can process fuels from different types of reactors on a common technical basis. Ease in handling the higher heat load of transuranium nuclides is also important. Pyroprocesses with the use of molten salts are regarded as the strong candidate for such recycling technology. In JAEA, the first laboratory for the high-temperature chemistry of Am and Cm has been established. The fundamental data will be combined with the computer code for predicting the molten-salts electrolytic processes.

Ogawa, Toru; Minato, Kazuo; Okamoto, Yoshihiro; Nishihara, Kenji

2007-01-01

385

Lipopolysaccharide mutants of Rhizobium meliloti are not defective in symbiosis  

SciTech Connect

Mutants of Rhizobium meliloti selected primarily for bacteriophage resistance fall into 13 groups. Mutants in the four best-characterized groups (class A, lpsB, lpsC, and class D), which map to the rhizobial chromosome, appear to affect lipopolysaccharide (LPS) as judged by the reactivity with monoclonal antibodies and behavior on sodium dodecyl sulfate-polyacrylamide gels of extracted LPS. Mutations in all 13 groups, in an otherwise wild-type genetic background, are Fix{sup +} on alfalfa. This suggests that LPS does not play a major role in symbiosis. Mutations in lpsB, however, are Fix{sup {minus}} in one particular genetic background, evidently because of the cumulative effect of several independent background mutations. In addition, an auxotrophic mutation evidently equivalent to Escherichia coli carAB is Fix{sup {minus}} on alfalfa.

Clover, R.H.; Kieber, J.; Signer, E.R. (Massachusetts Institute of Technology, Cambridge (USA))

1989-07-01

386

Autophosphorylation of gatekeeper tyrosine by symbiosis receptor kinase.  

PubMed

Plant receptor-like kinases (RLKs) share their evolutionary origin with animal interleukin-1 receptor-associated kinase (IRAK)/Pelle family of soluble kinases and are distinguished by having tyrosine as 'gatekeeper'. This position is adjacent to the hinge region and is hidden in a hydrophobic pocket of the catalytic cleft of protein kinases and is therefore least probable to be a target for any modification. This communication illustrates the accessibility of the gatekeeper site (Y670) towards both autophosphorylation and dephosphorylation in the recombinant cytoplasmic domain of symbiosis receptor kinase from Arachis hypogaea (AhSYMRK). Autophosphorylation on gatekeeper tyrosine was detected prior to extraction but never under in vitro conditions. We hypothesize gatekeeper phosphorylation to be associated with synthesis/maturation of AhSYMRK and this phenomenon may be prevalent among RLKs. PMID:23962520

Samaddar, Sandip; Dutta, Ayan; Sinharoy, Senjuti; Paul, Anindita; Bhattacharya, Avisek; Saha, Sudip; Chien, Ko-Yi; Goshe, Michael B; Dasgupta, Maitrayee

2013-08-17

387

Foraging behavior and prey interactions by a guild of predators on various lifestages of Bemisia tabaci  

PubMed Central

The sweetpotato whitefly, Bemisia tabaci (Gennadius) is fed on by a wide variety of generalist predators, but there is little information on these predator-prey interactions. A laboratory investigation was conducted to quantify the foraging behavior of the adults of five common whitefly predators presented with a surfeit of whitefly eggs, nymphs, and adults. The beetles, Hippodamia convergens Guérin-Méneville and Collops vittatus (Say) fed mostly on whitefly eggs, but readily and rapidly preyed on all of the whitefly lifestages. The true bugs, Geocoris punctipes (Say) and Orius tristicolor (Say) preyed almost exclusively on adult whiteflies, while Lygus hesperus Knight preyed almost exclusively on nymphs. The true bugs had much longer prey handling times than the beetles and spent much more of their time feeding (35–42%) than the beetles (6–7%). These results indicate that generalist predators vary significantly in their interaction with this host, and that foraging behavior should be considered during development of a predator-based biological control program for B. tabaci. Abbreviation: ELISA enzyme-linked immunosorbent assay

Hagler, James R.; Jackson, Charles G.; Isaacs, Rufus; Machtley, Scott A.

2004-01-01

388

The Laccaria and Tuber Genomes Reveal Unique Signatures of Mycorrhizal Symbiosis Evolution (2010 JGI User Meeting)  

SciTech Connect

Francis Martin from the French agricultural research institute INRA talks on how "The Laccaria and Tuber genomes reveal unique signatures of mycorrhizal symbiosis evolution" on March 24, 2010 at the 5th Annual DOE JGI User Meeting

Knapp, Steve

2010-03-24

389

Differential Effects of Rare Specific Flavonoids on Compatible and Incompatible Strains in the Myrica gale-Frankia Actinorhizal Symbiosis? †  

PubMed Central

Plant secondary metabolites, and specifically phenolics, play important roles when plants interact with their environment and can act as weapons or positive signals during biotic interactions. One such interaction, the establishment of mutualistic nitrogen-fixing symbioses, typically involves phenolic-based recognition mechanisms between host plants and bacterial symbionts during the early stages of interaction. While these mechanisms are well studied in the rhizobia-legume symbiosis, little is known about the role of plant phenolics in the symbiosis between actinorhizal plants and Frankia genus strains. In this study, the responsiveness of Frankia strains to plant phenolics was correlated with their symbiotic compatibility. We used Myrica gale, a host species with narrow symbiont specificity, and a set of compatible and noncompatible Frankia strains. M. gale fruit exudate phenolics were extracted, and 8 dominant molecules were purified and identified as flavonoids by high-resolution spectroscopic techniques. Total fruit exudates, along with two purified dihydrochalcone molecules, induced modifications of bacterial growth and nitrogen fixation according to the symbiotic specificity of strains, enhancing compatible strains and inhibiting incompatible ones. Candidate genes involved in these effects were identified by a global transcriptomic approach using ACN14a strain whole-genome microarrays. Fruit exudates induced differential expression of 22 genes involved mostly in oxidative stress response and drug resistance, along with the overexpression of a whiB transcriptional regulator. This work provides evidence for the involvement of plant secondary metabolites in determining symbiotic specificity and expands our understanding of the mechanisms, leading to the establishment of actinorhizal symbioses.

Popovici, Jean; Comte, Gilles; Bagnarol, Emilie; Alloisio, Nicole; Fournier, Pascale; Bellvert, Floriant; Bertrand, Cedric; Fernandez, Maria P.

2010-01-01

390

Role of arbuscular mycorrhizal symbiosis in root mineral uptake under CaCO 3 stress  

Microsoft Academic Search

This study investigated the effects of increasing CaCO3 concentrations (0, 5, 10, 20 mM) on arbuscular mycorrhizal (AM) symbiosis establishment as well as on chicory root growth\\u000a and mineral nutrient uptake in a monoxenic system. Although CaCO3 treatments significantly decreased root growth and altered the symbiosis-related development steps of the AM fungus Rhizophagus irregularis (germination, germination hypha elongation, root colonization rate,

Sonia Labidi; Fayçal Ben Jeddi; Benoit Tisserant; Djouher Debiane; Salah Rezgui; Anne Grandmougin-Ferjani; Anissa Lounès-Hadj Sahraoui

391

[Role of allelopathic compositions in the regulation and development of legume-rhizobial symbiosis].  

PubMed

It was discovered that aromatic compounds isolated from root exudates of three legume species (Pisum sativum L., Vicia faba L. var. major Hartz, and Glycine max L. MERR) and identified as N-phenyl-2-naphthyl amine, dibutyl, and dioctyl esters of orthophthalic acid, which are known to work as negative allelopathic substances, are involved in the regulation of legume-rhizobial symbiosis formation after the inoculation of roots with rhizobia under unfavorable conditions for symbiosis. PMID:23035572

Makarova, L E; Smirnov, V I; Klyba, L V; Petrova, I G; Dudareva, L V

392

Carbon availability triggers fungal nitrogen uptake and transport in arbuscular mycorrhizal symbiosis  

PubMed Central

The arbuscular mycorrhizal (AM) symbiosis, formed between the majority of land plants and ubiquitous soil fungi of the phylum Glomeromycota, is responsible for massive nutrient transfer and global carbon sequestration. AM fungi take up nutrients from the soil and exchange them against photosynthetically fixed carbon (C) from the host. Recent studies have demonstrated that reciprocal reward strategies by plant and fungal partners guarantee a “fair trade” of phosphorus against C between partners [Kiers ET, et al. (2011) Science 333:880–882], but whether a similar reward mechanism also controls nitrogen (N) flux in the AM symbiosis is not known. Using mycorrhizal root organ cultures, we manipulated the C supply to the host and fungus and followed the uptake and transport of N sources in the AM symbiosis, the enzymatic activities of arginase and urease, and fungal gene expression in the extraradical and intraradical mycelium. We found that the C supply of the host plant triggers the uptake and transport of N in the symbiosis, and that the increase in N transport is orchestrated by changes in fungal gene expression. N transport in the symbiosis is stimulated only when the C is delivered by the host across the mycorrhizal interface, not when C is supplied directly to the fungal extraradical mycelium in the form of acetate. These findings support the importance of C flux from the root to the fungus as a key trigger for N uptake and transport and provide insight into the N transport regulation in the AM symbiosis.

Fellbaum, Carl R.; Gachomo, Emma W.; Beesetty, Yugandhar; Choudhari, Sulbha; Strahan, Gary D.; Pfeffer, Philip E.; Kiers, E. Toby; Bucking, Heike

2012-01-01

393

Marine reserves reduce risk of climate-driven phase shift by reinstating size- and habitat-specific trophic interactions.  

PubMed

Spatial closures in the marine environment are widely accepted as effective conservation and fisheries management tools. Given increasing human-derived stressors acting on marine ecosystems, the need for such effective action is urgently clear. Here we explore mechanisms underlying the utility of marine reserves to reinstate trophic dynamics and to increase resilience of kelp beds against climate-driven phase shift to sea urchin barrens on the rapidly warming Tasmanian east coast. Tethering and tagging experiments were used to examine size- and shelter-specific survival of the range-extending sea urchin Centrostephanus rodgersii (Diadematidae) translocated to reefs inside and outside no-take Tasmanian marine reserves. Results show that survival rates of C. rodgersii exposed on flat reef substratum by tethering were approximately seven times (small urchins 10.1 times; large urchins 6.1 times) lower on protected reef within marine reserve boundaries (high abundance of large predatory-capable lobsters) compared to fished reef (large predatory lobsters absent). When able to seek crevice shelter, tag-resighting models estimated that mortality rates of C. rodgersii were lower overall but remained 3.3 times (small urchins 2.1 times; large urchins 6.4 times) higher in the presence of large lobsters inside marine reserves, with higher survival of small urchins owing to greater access to crevices relative to large urchins. Indeed, shelter was 6.3 times and 3.1 times more important to survival of small and large urchins, respectively, on reserved relative to fished reef. Experimental results corroborate with surveys throughout the range extension region, showing greater occurrence of overgrazing on high-relief rocky habitats where shelter for C. rodgersii is readily available. This shows that ecosystem impacts mediated by range extension of such habitat-modifying organisms will be heterogeneous in space, and that marine systems with a more natural complement of large and thus functional predators, as achievable within no-take reserves, will minimize local risk of phase shifts by reinstating size and habitat-specific predator-prey dynamics eroded by fishing. Importantly, our findings also highlight the crucial need to account for the influence of size dynamics and habitat complexity on rates of key predator-prey interactions when managing expectations of ecosystem-level responses within marine reserve boundaries. PMID:22827131

Ling, S D; Johnson, C R

2012-06-01

394

Life at the limits: peculiar features of lichen symbiosis related to extreme environmental factors  

NASA Astrophysics Data System (ADS)

A lichen is a symbiotic association formed by a mycobiont (fungi), a photobiont (algae) and/or a cyanobacteria. The special symbiotic contact and interaction between the bionts in a lichen is a prerequisite for maintainance of viability for each of them during influences by harsh environmental factors. In nature parameters like UV radiation, low or high temperatures and dryness may have a destructive impact on all life functions of an organism. But with lichens the evolution has created a peculiar symbiosis which enables a wide variety of lichen species to colonize habitats where their separate bionts would not be able to survive. The results of our investigations are demonstrating these aspects (de Vera et al. 2003, 2004).We have already investigated the viability of the entire lichen thallus, the embedded spores in lichen apothecia (fruiting bodies) as well as the isolated spores and isolated photobionts after exposure to most extreme conditions caused by simulated space parameters as extreme UV radiation and vacuum. The results presented here focuse on the survival capacity of the isolated photobionts from the two lichen species Xanthoria elegans and Fulgensia bracteata which are not protected by the fungal structure of the lichen thallus. They are based on examinations using a Confocal Laser Scanning Microscopy (CLSM), analysed by modern methods of the Image Tool Program and by culture experiments. In contrast to photobionts embedded in the entire lichen thallus the isolated photobionts are much more sensitve to the extreme conditions of UV radiation and vaccum: while 50 % of the bionts in an entire lichen thallus are able to cope with simulated extreme space conditions (UV-radiation: ? quad ? 160nm and vacuum: p = 10-5 Pa) during an exposure time of 2 weeks, the viability of the isolated photobiont cells was already decreasing after 2 hours of exposure. All photobiont cells were inactivated after longer exposure times of about 8 hours. Further more analysis concerning the UV and vacuum effect on the cultured mycobiont will demonstrate the peculiar function of symbiosis in a lichen system to withstand extreme environmental conditions. References: de Vera JP et al. 2003, Int. J. Astrobiol. 1 (4), 285-293 de Vera JP et al. 2004, Adv. Space Res. (in press)

de Vera, J.-P.; Horneck, G.; Rettberg, P.; Ott, S.

395

Arbuscular Mycorrhiza-Specific Signaling in Rice Transcends the Common Symbiosis Signaling Pathway[W  

PubMed Central

Knowledge about signaling in arbuscular mycorrhizal (AM) symbioses is currently restricted to the common symbiosis (SYM) signaling pathway discovered in legumes. This pathway includes calcium as a second messenger and regulates both AM and rhizobial symbioses. Both monocotyledons and dicotyledons form symbiotic associations with AM fungi, and although they differ markedly in the organization of their root systems, the morphology of colonization is similar. To identify and dissect AM-specific signaling in rice (Oryza sativa), we developed molecular phenotyping tools based on gene expression patterns that monitor various steps of AM colonization. These tools were used to distinguish common SYM-dependent and -independent signaling by examining rice mutants of selected putative legume signaling orthologs predicted to be perturbed both upstream (CASTOR and POLLUX) and downstream (CCAMK and CYCLOPS) of the central, calcium-spiking signal. All four mutants displayed impaired AM interactions and altered AM-specific gene expression patterns, therefore demonstrating functional conservation of SYM signaling between distant plant species. In addition, differential gene expression patterns in the mutants provided evidence for AM-specific but SYM-independent signaling in rice and furthermore for unexpected deviations from the SYM pathway downstream of calcium spiking.

Gutjahr, Caroline; Banba, Mari; Croset, Vincent; An, Kyungsook; Miyao, Akio; An, Gynheung; Hirochika, Hirohiko; Imaizumi-Anraku, Haruko; Paszkowski, Uta

2008-01-01

396

Mutualistic mycorrhiza-like symbiosis in the most ancient group of land plants.  

PubMed

Over 35 years ago, it was hypothesized that mutualistic symbiotic soil fungi assisted land plants in their initial colonization of terrestrial environments. This important idea has become increasingly established with palaeobotanical and molecular investigations dating the interactions between arbuscular mycorrhizal fungi (AMF) and land plants to at least 400?Ma, but the functioning of analogous partnerships in 'lower' land plants remains unknown. In this study, we show with multifactorial experiments that colonization of a complex thalloid liverwort, a member of the most ancient extant clade of land plants, with AMF significantly promotes photosynthetic carbon uptake, growth and asexual reproduction. Plant fitness increased through fungal-enhanced acquisition of phosphorus and nitrogen from soil, with each plant supporting 100-400?m of AMF mycelia. A simulated CO(2)-rich atmosphere, similar to that of the Palaeozoic when land plants originated, significantly amplified the net benefits of AMF and likely selection pressures for establishment of the symbiosis. Our analyses provide essential missing functional evidence supporting AMF symbionts as drivers of plant terrestrialization in early Palaeozoic land ecosystems. PMID:21045821

Humphreys, Claire P; Franks, Peter J; Rees, Mark; Bidartondo, Martin I; Leake, Jonathan R; Beerling, David J

2010-11-02

397

A single-cell view of ammonium assimilation in coral-dinoflagellate symbiosis.  

PubMed

Assimilation of inorganic nitrogen from nutrient-poor tropical seas is an essential challenge for the endosymbiosis between reef-building corals and dinoflagellates. Despite the clear evidence that reef-building corals can use ammonium as inorganic nitrogen source, the dynamics and precise roles of host and symbionts in this fundamental process remain unclear. Here, we combine high spatial resolution ion microprobe imaging (NanoSIMS) and pulse-chase isotopic labeling in order to track the dynamics of ammonium incorporation within the intact symbiosis between the reef-building coral Acropora aspera and its dinoflagellate symbionts. We demonstrate that both dinoflagellate and animal cells have the capacity to rapidly fix nitrogen from seawater enriched in ammonium (in less than one hour). Further, by establishing the relative strengths of the capability to assimilate nitrogen for each cell compartment, we infer that dinoflagellate symbionts can fix 14 to 23 times more nitrogen than their coral host cells in response to a sudden pulse of ammonium-enriched seawater. Given the importance of nitrogen in cell maintenance, growth and functioning, the capability to fix ammonium from seawater into the symbiotic system may be a key component of coral nutrition. Interestingly, this metabolic response appears to be triggered rapidly by episodic nitrogen availability. The methods and results presented in this study open up for the exploration of dynamics and spatial patterns associated with metabolic activities and nutritional interactions in a multitude of organisms that live in symbiotic relationships. PMID:22222466

Pernice, Mathieu; Meibom, Anders; Van Den Heuvel, Annamieke; Kopp, Christophe; Domart-Coulon, Isabelle; Hoegh-Guldberg, Ove; Dove, Sophie

2012-01-05

398

SymGRASS: a database of sugarcane orthologous genes involved in arbuscular mycorrhiza and root nodule symbiosis  

PubMed Central

Background The rationale for gathering information from plants procuring nitrogen through symbiotic interactions controlled by a common genetic program for a sustainable biofuel production is the high energy demanding application of synthetic nitrogen fertilizers. We curated sequence information publicly available for the biofuel plant sugarcane, performed an analysis of the common SYM pathway known to control symbiosis in other plants, and provide results, sequences and literature links as an online database. Methods Sugarcane sequences and informations were downloaded from the nucEST database, cleaned and trimmed with seqclean, assembled with TGICL plus translating mapping method, and annotated. The annotation is based on BLAST searches against a local formatted plant Uniprot90 generated with CD-HIT for functional assignment, rpsBLAST to CDD database for conserved domain analysis, and BLAST search to sorghum's for Gene Ontology (GO) assignment. Gene expression was normalized according the Unigene standard, presented as ESTs/100 kb. Protein sequences known in the SYM pathway were used as queries to search the SymGRASS sequence database. Additionally, antimicrobial peptides described in the PhytAMP database served as queries to retrieve and generate expression profiles of these defense genes in the libraries compared to the libraries obtained under symbiotic interactions. Results We describe the SymGRASS, a database of sugarcane orthologous genes involved in arbuscular mycorrhiza (AM) and root nodule (RN) symbiosis. The database aggregates knowledge about sequences, tissues, organ, developmental stages and experimental conditions, and provides annotation and level of gene expression for sugarcane transcripts and SYM orthologous genes in sugarcane through a web interface. Several candidate genes were found for all nodes in the pathway, and interestingly a set of symbiosis specific genes was found. Conclusions The knowledge integrated in SymGRASS may guide studies on molecular, cellular and physiological mechanisms by which sugarcane controls the establishment and efficiency of endophytic associations. We believe that the candidate sequences for the SYM pathway together with the pool of exclusively expressed tentative consensus (TC) sequences are crucial for the design of molecular studies to unravel the mechanisms controlling the establishment of symbioses in sugarcane, ultimately serving as a basis for the improvement of grass crops.

2013-01-01

399

Interactive Resource Planning-An Anticipative Concept in the Simulation-Based Decision Support System EXPOSIM  

NASA Astrophysics Data System (ADS)

In our research we intend to use experiments to study human behavior in a simulation environment based on a simple Lotka-Volterra predator-prey ecology. The aim is to study the influence of participants' harvesting strategies and certain personality traits derived from [1] on the outcome in terms of sustainability and economic performance. Such an approach is embedded in a research program which intends to develop and understand interactive resource planning processes. We present the general framework as well as the new decision support system EXPOSIM. The key element is the combination of experimental design, analytical understanding of time-discrete systems (especially Lotka-Volterra systems) and economic performance. In the first part, the general role of laboratory experiments is discussed. The second part summarizes the concept of sustainable development. It is taken from [18]. As we use Lotka-Volterra systems as the basis for our simulations a theoretical framework is described afterwards. It is possible to determine optimal behavior for those systems. The empirical setting is based on the empirical approach that the subjects are put into the position of a decision-maker. They are able to model the environment in such a way that harvesting can be observed. We suggest an experimental setting which might lead to new insights in an anticipatory sense.

Leopold-Wildburger, Ulrike; Pickl, Stefan

2008-10-01

400

Mechanisms driving change: altered species interactions and ecosystem function through global warming.  

PubMed

1. We review the mechanisms behind ecosystem functions, the processes that facilitate energy transfer along food webs, and the major processes that allow the cycling of carbon, oxygen and nitrogen, and use case studies to show how these have already been, and will continue to be, altered by global warming. 2. Increased temperatures will affect the interactions between heterotrophs and autotrophs (e.g. pollination and seed dispersal), and between heterotrophs (e.g. predators-prey, parasites/pathogens-hosts), with generally negative ramifications for important ecosystem services (functions that provide direct benefit to human society such as pollination) and potential for heightened species co-extinction rates. 3. Mitigation of likely impacts of warming will require, in particular, the maintenance of species diversity as insurance for the provision of basic ecosystem services. Key to this will be long-term monitoring and focused research that seek to maintain ecosystem resilience in the face of global warming. 4. We provide guidelines for pursuing research that quantifies the nexus between ecosystem function and global warming. These include documentation of key functional species groups within systems, and understanding the principal outcomes arising from direct and indirect effects of a rapidly warming environment. Localized and targeted research and monitoring, complemented with laboratory work, will determine outcomes for resilience and guide adaptive conservation responses and long-term planning. PMID:20487086

Traill, Lochran W; Lim, Matthew L M; Sodhi, Navjot S; Bradshaw, Corey J A

2010-05-11

401

Iron: an essential micronutrient for the legume-rhizobium symbiosis  

PubMed Central

Legumes, which develop a symbiosis with nitrogen-fixing bacteria, have an increased demand for iron. Iron is required for the synthesis of iron-containing proteins in the host, including the highly abundant leghemoglobin, and in bacteroids for nitrogenase and cytochromes of the electron transport chain. Deficiencies in iron can affect initiation and development of the nodule. Within root cells, iron is chelated with organic acids such as citrate and nicotianamine and distributed to other parts of the plant. Transport to the nitrogen-fixing bacteroids in infected cells of nodules is more complicated. Formation of the symbiosis results in bacteroids internalized within root cortical cells of the legume where they are surrounded by a plant-derived membrane termed the symbiosome membrane (SM). This membrane forms an interface that regulates nutrient supply to the bacteroid. Consequently, iron must cross this membrane before being supplied to the bacteroid. Iron is transported across the SM as both ferric and ferrous iron. However, uptake of Fe(II) by both the symbiosome and bacteroid is faster than Fe(III) uptake. Members of more than one protein family may be responsible for Fe(II) transport across the SM. The only Fe(II) transporter in nodules characterized to date is GmDMT1 (Glycine max divalent metal transporter 1), which is located on the SM in soybean. Like the root plasma membrane, the SM has ferric iron reductase activity. The protein responsible has not been identified but is predicted to reduce ferric iron accumulated in the symbiosome space prior to uptake by the bacteroid. With the recent publication of a number of legume genomes including Medicago truncatula and G. max, a large number of additional candidate transport proteins have been identified. Members of the NRAMP (natural resistance-associated macrophage protein), YSL (yellow stripe-like), VIT (vacuolar iron transporter), and ZIP (Zrt-, Irt-like protein) transport families show enhanced expression in nodules and are expected to play a role in the transport of iron and other metals across symbiotic membranes.

Brear, Ella M.; Day, David A.; Smith, Penelope M. C.

2013-01-01

402

The importance of phytoplankton size in mediating trophic interactions within the plankton of a southern African estuary  

NASA Astrophysics Data System (ADS)

The influence of the phytoplankton size composition in mediating the trophic interactions between the bacteria, phytoplankton, microheterotrophs (<200 ?m) and mesozooplankton (>200 ?m) was investigated on three occasions in a warm temperate, temporarily open/closed estuary situated along the southern African coastline. Results of the investigation indicated that the microheterotrophs represented the most important consumers of bacteria and chlorophyll (chl)-a <5.0 ?m. The low impact of the mesozooplankton on the bacteria and chl-a <5.0 ?m during the study appeared to be related to the inability of the larger zooplankton to feed efficiently on small particles. During those periods when total chl-a concentration was dominated by picophytoplankton (<2.0 ?m) and microphytoplankton (>20 ?m), mesozooplankton were unable to feed efficiently on the chl-a due to feeding constraints. In response to the unfavorable size structure of the phytoplankton assemblages, mesozooplankton appeared to consume the microheterotrophs. The negative impact of the mesozooplankton on the microheterotrophs resulted in a decrease in the impact of these organisms on the bacteria and the chl-a <5.0 ?m. This result is consistent with the predator-prey cascades. On the other hand, when the total chl-a was dominated by nanophytoplankton (2 20 ?m), mesozooplankton were able to feed directly on the phytoplankton. Results of the study indicate that size structure of the phytoplankton assemblages within estuaries plays an important role in mediating the trophic interactions between the various components of the plankton food web.

Froneman, P. W.

2006-12-01

403

The role of iron uptake in pathogenicity and symbiosis in Photorhabdus luminescens TT01  

PubMed Central

Background Photorhabdus are Gram negative bacteria that are pathogenic to insect larvae whilst also having a mutualistic interaction with nematodes from the family Heterorhabditis. Iron is an essential nutrient and bacteria have different mechanisms for obtaining both the ferrous (Fe2+) and ferric (Fe3+) forms of this metal from their environments. In this study we were interested in analyzing the role of Fe3+ and Fe2+ iron uptake systems in the ability of Photorhabdus to interact with its invertebrate hosts. Results We constructed targeted deletion mutants of exbD, feoABC and yfeABCD in P. luminescens TT01. The exbD mutant was predicted to be crippled in its ability to obtain Fe3+ and we show that this mutant does not grow well in iron-limited media. We also show that this mutant was avirulent to the insect but was unaffected in its symbiotic interaction with Heterorhabditis. Furthermore we show that a mutation in feoABC (encoding a predicted Fe2+ permease) was unaffected in both virulence and symbiosis whilst the divalent cation transporter encoded by yfeABCD is required for virulence in the Tobacco Hornworm, Manduca sexta (Lepidoptera) but not in the Greater Wax Moth, Galleria mellonella (Lepidoptera). Moreover the Yfe transporter also appears to have a role during colonization of the IJ stage of the nematode. Conclusion In this study we show that iron uptake (via the TonB complex and the Yfe transporter) is important for the virulence of P. luminescens to insect larvae. Moreover this study also reveals that the Yfe transporter appears to be involved in Mn2+-uptake during growth in the gut lumen of the IJ nematode. Therefore, the Yfe transporter in P. luminescens TT01 is important during colonization of both the insect and nematode and, moreover, the metal ion transported by this pathway is host-dependent.

2010-01-01

404

Paracatenula, an ancient symbiosis between thiotrophic Alphaproteobacteria and catenulid flatworms  

PubMed Central

Harnessing chemosynthetic symbionts is a recurring evolutionary strategy. Eukaryotes from six phyla as well as one archaeon have acquired chemoautotrophic sulfur-oxidizing bacteria. In contrast to this broad host diversity, known bacterial partners apparently belong to two classes of bacteria—the Gamma- and Epsilonproteobacteria. Here, we characterize the intracellular endosymbionts of the mouthless catenulid flatworm genus Paracatenula as chemoautotrophic sulfur-oxidizing Alphaproteobacteria. The symbionts of Paracatenula galateia are provisionally classified as “Candidatus Riegeria galateiae” based on 16S ribosomal RNA sequencing confirmed by fluorescence in situ hybridization together with functional gene and sulfur metabolite evidence. 16S rRNA gene phylogenetic analysis shows that all 16 Paracatenula species examined harbor host species-specific intracellular Candidatus Riegeria bacteria that form a monophyletic group within the order Rhodospirillales. Comparing host and symbiont phylogenies reveals strict cocladogenesis and points to vertical transmission of the symbionts. Between 33% and 50% of the body volume of the various worm species is composed of bacterial symbionts, by far the highest proportion among all known endosymbiotic associations between bacteria and metazoans. This symbiosis, which likely originated more than 500 Mya during the early evolution of flatworms, is the oldest known animal–chemoautotrophic bacteria association. The distant phylogenetic position of the symbionts compared with other mutualistic or parasitic Alphaproteobacteria promises to illuminate the common genetic predispositions that have allowed several members of this class to successfully colonize eukaryote cells.

Gruber-Vodicka, Harald Ronald; Dirks, Ulrich; Leisch, Nikolaus; Stoecker, Kilian; Bulgheresi, Silvia; Heindl, Niels Robert; Horn, Matthias; Lott, Christian; Loy, Alexander; Wagner, Michael; Ott, Jorg

2011-01-01

405

The dawn of symbiosis between plants and fungi  

PubMed Central

The colonization of land by plants relied on fundamental biological innovations, among which was symbiosis with fungi to enhance nutrient uptake. Here we present evidence that several species representing the earliest groups of land plants are symbiotic with fungi of the Mucoromycotina. This finding brings up the possibility that terrestrialization was facilitated by these fungi rather than, as conventionally proposed, by members of the Glomeromycota. Since the 1970s it has been assumed, largely from the observation that vascular plant fossils of the early Devonian (400 Ma) show arbuscule-like structures, that fungi of the Glomeromycota were the earliest to form mycorrhizas, and evolutionary trees have, until now, placed Glomeromycota as the oldest known lineage of endomycorrhizal fungi. Our observation that Endogone-like fungi are widely associated with the earliest branching land plants, and give way to glomeromycotan fungi in later lineages, raises the new hypothesis that members of the Mucoromycotina rather than the Glomeromycota enabled the establishment and growth of early land colonists.

Bidartondo, Martin I.; Read, David J.; Trappe, James M.; Merckx, Vincent; Ligrone, Roberto; Duckett, Jeffrey G.

2011-01-01

406

The dawn of symbiosis between plants and fungi.  

PubMed

The colonization of land by plants relied on fundamental biological innovations, among which was symbiosis with fungi to enhance nutrient uptake. Here we present evidence that several species representing the earliest groups of land plants are symbiotic with fungi of the Mucoromycotina. This finding brings up the possibility that terrestrialization was facilitated by these fungi rather than, as conventionally proposed, by members of the Glomeromycota. Since the 1970s it has been assumed, largely from the observation that vascular plant fossils of the early Devonian (400 Ma) show arbuscule-like structures, that fungi of the Glomeromycota were the earliest to form mycorrhizas, and evolutionary trees have, until now, placed Glomeromycota as the oldest known lineage of endomycorrhizal fungi. Our observation that Endogone-like fungi are widely associated with the earliest branching land plants, and give way to glomeromycotan fungi in later lineages, raises the new hypothesis that members of the Mucoromycotina rather than the Glomeromycota enabled the establishment and growth of early land colonists. PMID:21389014

Bidartondo, Martin I; Read, David J; Trappe, James M; Merckx, Vincent; Ligrone, Roberto; Duckett, Jeffrey G

2011-03-09

407

Metabolic symbiosis in cancer: refocusing the Warburg lens.  

PubMed

Using relatively primitive tools in the 1920s, Otto Warburg demonstrated that tumor cells show an increased dependence on glycolysis to meet their energy needs, regardless of whether they were well-oxygenated or not. High rates of glucose uptake, fueling glycolysis, are now used clinically to identify cancer cells. However, the Warburg effect does not account for the metabolic diversity that has been observed amongst cancer cells nor the influences that might direct such diversity. Modern tools have shown that the oncogenes, variable hypoxia levels, and the utilization of different carbon sources affect tumor evolution. These influences may produce metabolic symbiosis, in which lactate from a hypoxic, glycolytic tumor cell population fuels ATP production in the oxygenated region of a tumor. Lactate, once considered a waste product of glycolysis, is an important metabolite for oxidative phosphorylation in many tissues. While much is known about how muscle and the brain use lactate in oxidative phosphorylation, the contribution of lactate in tumor bioenergetics is less defined. A refocused perspective of cancer metabolism that recognizes metabolic diversity within a tumor offers novel therapeutic targets by which cancer cells may be starved from their fuel sources, and thereby become more sensitive to traditional cancer treatments. PMID:22228080

Nakajima, Erica C; Van Houten, Bennett

2012-01-06

408

Cell and developmental biology of arbuscular mycorrhiza symbiosis.  

PubMed

The default mineral nutrient acquisition strategy of land plants is the symbiosis with arbuscular mycorrhiza (AM) fungi. Research into the cell and developmental biology of AM revealed fascinating insights into the plasticity of plant cell development and of interorganismic communication. It is driven by the prospect of increased exploitation of AM benefits for sustainable agriculture. The plant cell developmental program for intracellular accommodation of AM fungi is activated by a genetically defined signaling pathway involving calcium spiking in the nucleus as second messenger. Calcium spiking is triggered by chitooligosaccharides released by AM fungi that are probably perceived via LysM domain receptor kinases. Fungal infection and calcium spiking are spatiotemporally coordinated, and only cells committed to accommodating the fungus undergo high-frequency spiking. Delivery of mineral nutrients by AM fungi occurs at tree-shaped hyphal structures, the arbuscules, in plant cortical cells. Nutrients are taken up at a plant-derived periarbuscular membrane, which surrounds fungal hyphae and carries a specific transporter composition that is of direct importance for symbiotic efficiency. An elegant study has unveiled a new and unexpected mechanism for specific protein localization to the periarbuscular membrane, which relies on the timing of gene expression to synchronize protein biosynthesis with a redirection of secretion. The control of AM development by phytohormones is currently subject to active investigation and has led to the rediscovery of strigolactones. Nearly all tested phytohormones regulate AM development, and major insights into the mechanisms of this regulation are expected in the near future. PMID:24099088

Gutjahr, Caroline; Parniske, Martin

2013-10-01

409

Microgravity effects on the legume/Rhizobium symbiosis  

NASA Astrophysics Data System (ADS)

Symbiotic nitrogen fixation is of critical importance to world agriculture and likely will be a critical part of life support systems developed for prolonged missions in space. Bacteroid formation, an essential step in an effective Dutch White Clover/Rhizobium leguminosarum bv trifolii symbiosis, is induced by succinic acid which is produced by the plant and which is bound and incorporated by the bacterium. Aspirin mimics succinate in its role as a bacteroid inducer and measures of aspirin binding mimiced measurements of succinate binding. In normal gravity (1×g), rhizobium bacteria immediately bound relatively high levels of aspirin (or succinate) in a readily reversible manner. Within a few seconds a portion of this initially bound aspirin became irreversibly bound. In the microgravity environment aboard the NASA 930 aircraft, rhizobia did not display the initial reversible binding of succinate, but did display a similar kinetic pattern of irreversible binding, and ultimately bound 32% more succinate (Acta Astronautica 36:129-133, 1995.) In normal gravity succinate treated cells stop dividing and swell to their maximum size (twice the normal cell volume) within a time equivalent to the time required for two normal cell doublings. Swelling in microgravity was tested in FPA and BPM sample holders aboard the space shuttle (USML-1, and STS-54, 57, and 60.) The behavior of cells in the two sample holders was similar, and swelling behavior of cells in microgravity was identical to behavior in normal gravity.

Urban, James E.

1997-01-01

410

Host-Bacterial Symbiosis in Health and Disease  

PubMed Central

All animals live in symbiosis. Shaped by eons of co-evolution, host-bacterial associations have developed into prosperous relationships creating mechanisms for mutual benefits to both microbe and host. No better example exists in biology than the astounding numbers of bacteria harbored by the lower gastrointestinal tract of mammals. The mammalian gut represents a complex ecosystem consisting of an extraordinary number of resident commensal bacteria existing in homeostasis with the host’s immune system. Most impressive about this relationship may be the concept that the host not only tolerates, but has evolved to require colonization by beneficial microorganisms, known as commensals, for various aspects of immune development and function. The microbiota provides critical signals that promote maturation of immune cells and tissues, leading to protection from infections by pathogens. Gut bacteria also appear to contribute to non-infectious immune disorders such as inflammatory bowel disease and autoimmunity. How the microbiota influences host immune responses is an active area of research with important implications for human health. This review synthesizes emerging findings and concepts that describe the mutualism between the microbiota and mammals, specifically emphasizing the role of gut bacteria in shaping an immune response that mediates the balance between health and disease. Unlocking how beneficial bacteria affect the development of the immune system may lead to novel and natural therapies based on harnessing the immunomodulatory properties of the microbiota.

Chow, Janet; Lee, S. Melanie; Shen, Yue; Khosravi, Arya; Mazmanian, Sarkis K.

2011-01-01

411

Setting realistic recovery targets for two interacting endangered species, sea otter and northern abalone.  

PubMed

Failure to account for interactions between endangered species may lead to unexpected population dynamics, inefficient management strategies, waste of scarce resources, and, at worst, increased extinction risk. The importance of species interactions is undisputed, yet recovery targets generally do not account for such interactions. This shortcoming is a consequence of species-centered legislation, but also of uncertainty surrounding the dynamics of species interactions and the complexity of modeling such interactions. The northern sea otter (Enhydra lutris kenyoni) and one of its preferred prey, northern abalone (Haliotis kamtschatkana), are endangered species for which recovery strategies have been developed without consideration of their strong predator-prey interactions. Using simulation-based optimization procedures from artificial intelligence, namely reinforcement learning and stochastic dynamic programming, we combined sea otter and northern abalone population models with functional-response models and examined how different management actions affect population dynamics and the likelihood of achieving recovery targets for each species through time. Recovery targets for these interacting species were difficult to achieve simultaneously in the absence of management. Although sea otters were predicted to recover, achieving abalone recovery targets failed even when threats to abalone such as predation and poaching were reduced. A management strategy entailing a 50% reduction in the poaching of northern abalone was a minimum requirement to reach short-term recovery goals for northern abalone when sea otters were present. Removing sea otters had a marginally positive effect on the abalone population but only when we assumed a functional response with strong predation pressure. Our optimization method could be applied more generally to any interacting threatened or invasive species for which there are multiple conservation objectives. PMID:23083059

Chadès, Iadine; Curtis, Janelle M R; Martin, Tara G

2012-10-19

412

Thiol-based redox signaling in the nitrogen-fixing symbiosis  

PubMed Central

In nitrogen poor soils legumes establish a symbiotic interaction with rhizobia that results in the formation of root nodules. These are unique plant organs where bacteria differentiate into bacteroids, which express the nitrogenase enzyme complex that reduces atmospheric N 2 to ammonia. Nodule metabolism requires a tight control of the concentrations of reactive oxygen and nitrogen species (RONS) so that they can perform useful signaling roles while avoiding nitro-oxidative damage. In nodules a thiol-dependent regulatory network that senses, transmits and responds to redox changes is starting to be elucidated. A combination of enzymatic, immunological, pharmacological and molecular analyses has allowed us to conclude that glutathione and its legume-specific homolog, homoglutathione, are abundant in meristematic and infected cells, that their spatio-temporally distribution is correlated with the corresponding (homo)glutathione synthetase activities, and that they are crucial for nodule development and function. Glutathione is at high concentrations in the bacteroids and at moderate amounts in the mitochondria, cytosol and nuclei. Less information is available on other components of the network. The expression of multiple isoforms of glutathione peroxidases, peroxiredoxins, thioredoxins, glutaredoxins and NADPH-thioredoxin reductases has been detected in nodule cells using antibodies and proteomics. Peroxiredoxins and thioredoxins are essential to regulate and in some cases to detoxify RONS in nodules. Further research is necessary to clarify the regulation of the expression and activity of thiol redox-active proteins in response to abiotic, biotic and developmental cues, their interactions with downstream targets by disulfide-exchange reactions, and their participation in signaling cascades. The availability of mutants and transgenic lines will be crucial to facilitate systematic investigations into the function of the various proteins in the legume-rhizobial symbiosis.

Frendo, Pierre; Matamoros, Manuel A.; Alloing, Genevieve; Becana, Manuel

2013-01-01

413

Genome-Wide Functional Divergence after the Symbiosis of Proteobacteria with Insects Unraveled through a Novel Computational Approach  

Microsoft Academic Search

Symbiosis has been among the most important evolutionary steps to generate biological complexity. The establishment of symbiosis required an intimate metabolic link between biological systems with different complexity levels. The strict endo-cellular symbiotic bacteria of insects are beautiful examples of the metabolic coupling between organisms belonging to different kingdoms, a eukaryote and a prokaryote. The host (eukaryote) provides the endosymbiont

Christina Toft; Tom A. Williams; Mario A. Fares

2009-01-01

414

Can rare positive interactions become common when large carnivores consume livestock?  

PubMed

Livestock populations in protected areas are viewed negatively because of their interaction with native ungulates through direct competition for food resources. However, livestock and native prey can also interact indirectly through their shared predator. Indirect interactions between two prey species occur when one prey modifies either the functional or numerical responses of a shared predator. This interaction is often manifested as negative effects (apparent competition) on one or both prey species through increased predation risk. But indirect interactions can also yield positive effects on a focal prey if the shared predator modifies its functional response toward increased consumption of an abundant and higher-quality alternative prey. Such a phenomenon between two prey species is underappreciated and overlooked in nature. Positive indirect effects can be expected to occur in livestock-dominated wildlife reserves containing large carnivores. We searched for such positive effects in Acacia-Zizhypus forests of India's Gir sanctuary where livestock (Bubalus bubalis and Bos indicus) and a coexisting native prey (chital deer, Axis axis) are consumed by Asiatic lions (Panthera leo persica). Chital vigilance was higher in areas with low livestock density than in areas with high livestock density. This positive indirect effect occurred because lion predation rates on livestock were twice as great where livestock were abundant than where livestock density was low. Positive indirect interactions mediated by shared predators may be more common than generally thought with rather major consequences for ecological understanding and conservation. We encourage further studies to understand outcomes of indirect interactions on long-term predator-prey dynamics in livestock-dominated protected areas. PMID:22624309

Sundararaj, Vijayan; McLaren, Brian E; Morris, Douglas W; Goyal, S P

2012-02-01

415

Stress tolerance in plants via habitat-adapted symbiosis  

USGS Publications Warehouse

We demonstrate that native grass species from coastal and geothermal habitats require symbiotic fungal endophytes for salt and heat tolerance, respectively. Symbiotically conferred stress tolerance is a habitat-specific phenomenon with geothermal endophytes conferring heat but not salt tolerance, and coastal endophytes conferring salt but not heat tolerance. The same fungal species isolated from plants in habitats devoid of salt or heat stress did not confer these stress tolerances. Moreover, fungal endophytes from agricultural crops conferred disease resistance and not salt or heat tolerance. We define habitat-specific, symbiotically-conferred stress tolerance as habitat-adapted symbiosis and hypothesize that it is responsible for the establishment of plants in high-stress habitats. The agricultural, coastal and geothermal plant endophytes also colonized tomato (a model eudicot) and conferred disease, salt and heat tolerance, respectively. In addition, the coastal plant endophyte colonized rice (a model monocot) and conferred salt tolerance. These endophytes have a broad host range encompassing both monocots and eudicots. Interestingly, the endophytes also conferred drought tolerance to plants regardless of the habitat of origin. Abiotic stress tolerance correlated either with a decrease in water consumption or reactive oxygen sensitivity/generation but not to increased osmolyte production. The ability of fungal endophytes to confer stress tolerance to plants may provide a novel strategy for mitigating the impacts of global climate change on agricultural and native plant communities.The ISME Journal (2008) 2, 404-416; doi:10.1038/ismej.2007.106; published online 7 February 2008. ?? 2008 International Society for Microbial Ecology All rights reserved.

Rodriguez, R. J.; Henson, J.; Van Volkenburgh, E.; Hoy, M.; Wright, L.; Beckwith, F.; Kim, Y. -O.; Redman, R. S.

2008-01-01

416

Périgord black truffle genome uncovers evolutionary origins and mechanisms of symbiosis.  

PubMed

The Périgord black truffle (Tuber melanosporum Vittad.) and the Piedmont white truffle dominate today's truffle market. The hypogeous fruiting body of T. melanosporum is a gastronomic delicacy produced by an ectomycorrhizal symbiont endemic to calcareous soils in southern Europe. The worldwide demand for this truffle has fuelled intense efforts at cultivation. Identification of processes that condition and trigger fruit body and symbiosis formation, ultimately leading to efficient crop production, will be facilitated by a thorough analysis of truffle genomic traits. In the ectomycorrhizal Laccaria bicolor, the expansion of gene families may have acted as a 'symbiosis toolbox'. This feature may however reflect evolution of this particular taxon and not a general trait shared by all ectomycorrhizal species. To get a better understanding of the biology and evolution of the ectomycorrhizal symbiosis, we report here the sequence of the haploid genome of T. melanosporum, which at approximately 125 megabases is the largest and most complex fungal genome sequenced so far. This expansion results from a proliferation of transposable elements accounting for approximately 58% of the genome. In contrast, this genome only contains approximately 7,500 protein-coding genes with very rare multigene families. It lacks large sets of carbohydrate cleaving enzymes, but a few of them involved in degradation of plant cell walls are induced in symbiotic tissues. The latter feature and the upregulation of genes encoding for lipases and multicopper oxidases suggest that T. melanosporum degrades its host cell walls during colonization. Symbiosis induces an increased expression of carbohydrate and amino acid transporters in both L. bicolor and T. melanosporum, but the comparison of genomic traits in the two ectomycorrhizal fungi showed that genetic predispositions for symbiosis-'the symbiosis toolbox'-evolved along different ways in ascomycetes and basidiomycetes. PMID:20348908

Martin, Francis; Kohler, Annegret; Murat, Claude; Balestrini, Raffaella; Coutinho, Pedro M; Jaillon, Olivier; Montanini, Barbara; Morin, Emmanuelle; Noel, Benjamin; Percudani, Riccardo; Porcel, Bettina; Rubini, Andrea; Amicucci, Antonella; Amselem, Joelle; Anthouard, Véronique; Arcioni, Sergio; Artiguenave, François; Aury, Jean-Marc; Ballario, Paola; Bolchi, Angelo; Brenna, Andrea; Brun, Annick; Buée, Marc; Cantarel, Brandi; Chevalier, Gérard; Couloux, Arnaud; Da Silva, Corinne; Denoeud, France; Duplessis, Sébastien; Ghignone, Stefano; Hilselberger, Benoît; Iotti, Mirco; Marçais, Benoît; Mello, Antonietta; Miranda, Michele; Pacioni, Giovanni; Quesneville, Hadi; Riccioni, Claudia; Ruotolo, Roberta; Splivallo, Richard; Stocchi, Vilberto; Tisserant, Emilie; Viscomi, Arturo Roberto; Zambonelli, Alessandra; Zampieri, Elisa; Henrissat, Bernard; Lebrun, Marc-Henri; Paolocci, Francesco; Bonfante, Paola; Ottonello, Simone; Wincker, Patrick

2010-03-28

417

Predation, individual variability and vertebrate population dynamics  

Microsoft Academic Search

Both predation and individual variation in life history traits influence population dynamics. Recent results from laboratory\\u000a predator–prey systems suggest that differences between individuals can also influence predator–prey dynamics when different\\u000a genotypes experience different predation-associated mortalities. Despite the growing number of studies in this field, there\\u000a is no synthesis identifying the overall importance of the interactions between predation and individual heterogeneity

Nathalie Pettorelli; Tim Coulson; Sarah M. Durant; Jean-Michel Gaillard

418

Parasites as predators: unifying natural enemy ecology  

Microsoft Academic Search

Parasitism and predation have long been considered analogous interactions. Yet by and large, ecologists continue to study parasite-host and predator-prey ecology separately. Here we discuss strengths and shortcomings of the parasite-as-predator analogy and its potential to provide new insights into both fields. Developments in predator-prey ecology, such as temporal risk allocation and associational resistance, can drive new hypotheses for parasite-host

Thomas R. Raffel; Lynn B. Martin; Jason R. Rohr

2008-01-01

419

Dual lattice model of the evolution of facultative symbiosis with continuous Prisoner's Dilemma game.  

PubMed

Mutualism is ubiquitous in nature and is thought to have played a key role in the history of life. However, how mutualism could evolve despite being prone to unilateral exploitation is a puzzling question in evolutionary ecology. Some theoretical studies have shown that spatial structure of habitat can facilitate the emergence and maintenance of mutualism. However, they are based on the simple assumption that the trait in question is discrete: each individual is either a mutualist or a non-mutualist. In this article I develop a simple simulation model of coevolution of facultative symbiosis using a one-shot continuous Prisoner's Dilemma game to investigate the evolutionary dynamics of mutualism between two species. In this model I assume continuous traits for both species from -1 (fully deceptive) to 1 (fully cooperative). The habitat has a dual-lattice structure, each layer is inhabited by one species. Interspecific interaction is restricted between two corresponding sites of the two layers. Without limitation on the magnitude of a single mutation, I find that mutualism can arise and persist when the intrinsic reproduction rate is low (but is above a threshold) and the benefit/cost ratio of the cooperative strategy is large, which is consistent with Yamamura et al. [2004. Evolution of mutualism through spatial effects. J. Theor. Biol. 226, 421-428]. In these cases, extreme antagonism often evolves starting from a neutral population that seems nearly stable, but once mutualism arises, the cooperative individuals quickly increase and both the populations eventually become mutualistic on average, although they are polymorphic. However, when the effect of a single mutation was limited to be small, extreme antagonism is much likely to dominate unless the intrinsic reproduction rate is low. When only one species is allowed to evolve, mutualism arises when the initial strategy of the other species is cooperative. Otherwise, excessive deception evolves in the former, and the latter often becomes driven to extinction. PMID:19409909

Ezoe, Hideo

2009-05-04

420

Insights into post-transcriptional regulation during legume-rhizobia symbiosis  

PubMed Central

During the past ten years, changes in the transcriptome have been assessed at different stages of the legume-rhizobia association by the use of DNA microarrays and, more recently, by RNA sequencing technologies. These studies allowed the identification of hundred or thousand of genes whose steady-state mRNA levels increase or decrease upon bacterial infection or in nodules as compared with uninfected roots. However, transcriptome based-approaches do not distinguish between mRNAs that are being actively translated, stored as messenger ribonucleoproteins (mRNPs) or targeted for degradation. Despite that the increase in steady-state levels of an mRNA does not necessarily correlate with an increase in abundance or activity of the encoded protein, this information has been commonly used to select genes that are candidates to play a role during nodule organogenesis or bacterial infection. Such criterion does not take into account the post-transcriptional mechanisms that contribute to the regulation of gene expression. One of such mechanisms, which has significant impact on gene expression, is the selective recruitment of mRNAs to the translational machinery.  Here, we review the post-transcriptional mechanisms that contribute to the regulation of gene expression in the context of the ecological and agronomical important symbiotic interaction established between roots of legumes and the nitrogen fixing bacteria collectively known as rhizobia. In addition, we discuss how the development of new technologies that allow the assessment of these regulatory layers would help to understand the genetic network governing legume rhizobia symbiosis.

Reynoso, Mauricio Alberto; Blanco, Flavio Antonio; Zanetti, Maria Eugenia

2013-01-01

421

Preferential Expulsion of Dividing Algal Cells as a Mechanism for Regulating Algal-Cnidarian Symbiosis  

Microsoft Academic Search

A wide range of both intrinsic and environmen- tal factors can influence the population dynamics of algae in symbiosis with marine cnidarians. The present study shows that loss of algae by expulsion from cnidarian hosts is one of the primary regulators of symbiont population density. Because there is a significant linear correlation between the rate of algal expulsion and the

GAREN BAGHDASARIAN; LEONARD MUSCATINE

2000-01-01

422

The Mutual Symbiosis between Inclusive Bi-Lingual Education and Multicultural Education  

ERIC Educational Resources Information Center

In this article the authors postulate a mutual symbiosis between multicultural and inclusive bi-lingual education. Combining bi-lingual and multicultural education to create a symbiotic relationship can stimulate reform in schools and can promote inclusive educational systems, thereby keeping native languages and cultures alive for minority…

Irby, Beverly J.; Tong, Fuhui; Lara-Alecio, Rafael

2011-01-01

423

Metabolic Complementarity and Genomics of the Dual Bacterial Symbiosis of Sharpshooters  

Microsoft Academic Search

Mutualistic intracellular symbiosis between bacteria and insects is a widespread phenomenon that has contributed to the global success of insects. The symbionts, by provisioning nutrients lacking from diets, allow various insects to occupy or dominate ecological niches that might otherwise be unavailable. One such insect is the glassy-winged sharpshooter (Homalodisca coagulata), which feeds on xylem fluid, a diet exceptionally poor

Dongying Wu; Sean C. Daugherty; Susan E. Van Aken; Grace H. Pai; Kisha L. Watkins; Hoda Khouri; Luke J. Tallon; Jennifer M. Zaborsky; Helen E. Dunbar; Phat L. Tran; Nancy A. Moran; Jonathan A. Eisen

2006-01-01

424

Two Medicago truncatula half-ABC transporters are essential for arbuscule development in arbuscular mycorrhizal symbiosis.  

PubMed

In the symbiotic association of plants and arbuscular mycorrhizal (AM) fungi, the fungal symbiont resides in the root cortical cells where it delivers mineral nutrients to its plant host through branched hyphae called arbuscules. Here, we report a Medicago truncatula mutant, stunted arbuscule (str), in which arbuscule development is impaired and AM symbiosis fails. In contrast with legume symbiosis mutants reported previously, str shows a wild-type nodulation phenotype. STR was identified by positional cloning and encodes a half-size ATP binding cassette (ABC) transporter of a subfamily (ABCG) whose roles in plants are largely unknown. STR is a representative of a novel clade in the ABCG subfamily, and its orthologs are highly conserved throughout the vascular plants but absent from Arabidopsis thaliana. The STR clade is unusual in that it lacks the taxon-specific diversification that is typical of the ABCG gene family. This distinct phylogenetic profile enabled the identification of a second AM symbiosis-induced half-transporter, STR2. Silencing of STR2 by RNA interference results in a stunted arbuscule phenotype identical to that of str. STR and STR2 are coexpressed constitutively in the vascular tissue, and expression is induced in cortical cells containing arbuscules. STR heterodimerizes with STR2, and the resulting transporter is located in the peri-arbuscular membrane where its activity is required for arbuscule development and consequently a functional AM symbiosis. PMID:20453115

Zhang, Quan; Blaylock, Laura A; Harrison, Maria J

2010-05-07

425

Rice phosphate transporters include an evolutionarily divergent gene specifically activated in arbuscular mycorrhizal symbiosis  

PubMed Central

Using a genome-wide approach, we asked how many transporter genes contribute to symbiotic phosphate uptake and analyzed their evolutionary conservation. Considering the sequenced rice genome at hand, only the Oryza sativa phosphate transporter (OsPT) gene OsPT11 was specifically induced during the arbuscular mycorrhizal symbiosis. This induction was confined to the root system and was tightly correlated with the degree of root colonization by Glomus intraradices. OsPT11 activation was independent of the nutritional status of the plant and phosphate availability in the rhizosphere. Moreover, infection of roots with the fungal pathogens Rhizoctonia solani and Fusarium moniliforme did not activate OsPT11, corroborating the high signal specificity for OsPT11 activation in the arbuscular mycorrhizal symbiosis. OsPT11 expression complemented a defect in phosphate uptake in a yeast strain mutated in its high-affinity Pi transporter (pho84), thereby confirming its function. Recently, a phosphate transporter gene in potato was shown to be induced during arbuscular mycorrhizal symbiosis. Assessment of the phylogenetic relationship of the rice and potato protein revealed that the rice is nonorthologous to the potato protein. Further, there are no structural commonalities in the promoter regions. Thus, although cytological and physiological features of the arbuscular mycorrhizal symbiosis seem to be conserved, the molecular components may differ significantly between distantly related plant species.

Paszkowski, Uta; Kroken, Scott; Roux, Christophe; Briggs, Steven P.

2002-01-01

426

Effects of nano-TiO2 on the agronomically-relevant Rhizobium-legume symbiosis  

Technology Transfer Automated Retrieval System (TEKTRAN)

The impact of nano-TiO2 on Rhizobium-legume symbiosis was studied using garden peas and the compatible bacterial partner Rhizobium leguminosarum bv. viciae 3841. Exposure to nano-TiO2 did not affect the germination of peas grown aseptically, nor did it impact the gross root structure. However, nano-...

427

THE FUNGUS DOES NOT TRANSFER CARBON TO OR BETWEEN ROOTS IN AN ARBUSCULAR MYCORRHIZAL SYMBIOSIS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Very large amounts of photosynthetically fixed carbon move from plants to their fungal partners in the Arbuscular Mycorrhizal (AM) symbiosis. There is also evidence for transfer of carbon in the reverse direction. However, the significance and even existence of fungus-to-plant carbon transfer has b...

428

The Mutual Symbiosis between Inclusive Bi-Lingual Education and Multicultural Education  

ERIC Educational Resources Information Center

|In this article the authors postulate a mutual symbiosis between multicultural and inclusive bi-lingual education. Combining bi-lingual and multicultural education to create a symbiotic relationship can stimulate reform in schools and can promote inclusive educational systems, thereby keeping native languages and cultures alive for minority…

Irby, Beverly J.; Tong, Fuhui; Lara-Alecio, Rafael

2011-01-01

429

The promiscuous larvae: flexibility in the establishment of symbiosis in corals  

NASA Astrophysics Data System (ADS)

Coral reefs thrive in part because of the symbiotic partnership between corals and Symbiodinium. While this partnership is one of the keys to the success of coral reef ecosystems, surprisingly little is known about many aspects of coral symbiosis, in particular the establishment and development of symbiosis in host species that acquire symbionts anew in each generation. More specifically, the point at which symbiosis is established (i.e., larva vs. juvenile) remains uncertain, as does the source of free-living Symbiodinium in the environment. In addition, the capacity of host and symbiont to form novel combinations is unknown. To explore patterns of initial association between host and symbiont, larvae of two species of Acropora were exposed to sediment collected from three locations on the Great Barrier Reef. A high proportion of larvae established symbiosis shortly after contact with sediments, and Acropora larvae were promiscuous, taking up multiple types of Symbiodinium. The Symbiodinium types acquired from the sediments reflected the symbiont assemblage within a wide range of cnidarian hosts at each of the three sites, suggesting potential regional differences in the free-living Symbiodinium assemblage. Coral larvae clearly have the capacity to take up Symbiodinium prior to settlement, and sediment is a likely source. Promiscuous larvae allow species to associate with Symbiodinium appropriate for potentially novel environments that may be experienced following dispersal.

Cumbo, V. R.; Baird, A. H.; van Oppen, M. J. H.

2013-03-01

430

Iron regulation of gene expression in the Bradyrhizobium japonicum/soybean symbiosis. Progress report.  

National Technical Information Service (NTIS)

We wish to address the question of whether iron plays a regulatory role in the Bradyrhizobium japonicum/soybeam symbiosis. Iron may be an important regulatory signal in planta as the bacteria must acquire iron from their plant hosts and iron-containing pr...

M. L. Guerinot

1992-01-01

431

Enigmatic dual symbiosis in the excretory organ of Nautilus macromphalus (Cephalopoda: Nautiloidea)  

Microsoft Academic Search

Symbiosis is an important driving force in metazoan evolution and the study of ancient lineages can provide an insight into the influence of symbiotic associations on morphological and physiological adaptations. In the 'living fossil' Nautilus, bacterial associations are found in the highly specialized pericardial appendage. This organ is responsible for most of the excretory processes (ultrafiltration, reabsorption and secretion) and

Mathieu Pernice; Silke Wetzel; Olivier Gros; Renata Boucher-Rodoni; Nicole Dubilier

2007-01-01

432

OBSERVATIONS ON THE SYMBIOSIS OF THE SEA ANEMONE STOICHACTIS AND THE POMACENTRID FISH, AMPHIPRION PERCULA  

Microsoft Academic Search

The partnership between certain tropical damselfishes and sea anemones has excited the interest of students of natural history for almost a century. The most significant investigations of the symbiosis have been those of Sluiter (1888), Ver wey (1930) and Gohar (1948), who have given us some knowledge of the ecology and behavioral characteristics of the animals. In 1947 Gudger reviewed

DEMOREST DAVENPORT; KENNETH S. NORRIS

433

The effect of pseudo-microgravity on the symbiosis of plants and microorganisms  

NASA Astrophysics Data System (ADS)

The symbiosis of plants and microorganisms is important to conduct agriculture under space environment. However, we have less knowledge on whether this kind of symbiosis can be established under space condition. We examined the functional compounds responsible to symbiosis between rhizobiaum and Lotus japonicus as a model of symbiotic combination. The existence of the substances for their symbiosis, some flavonoids, have already been known from the study of gene expression, but the detail structures have not yet been elucidated. Pseudomicrogravity was generated by the 3D-clinorotation. Twenty flavonoids were found in the extracts of 16 days plants of Lotus japonicus grown under the normal gravity by HPLC. Content of two flavonoids among them was affected by the infection of Mesorhizobium loti to them. It has a possibility that the two flavonoids were key substances for their combination process. The productions of those flavonoids were confirmed also under the pseudo-microgravity. The amount of one flavonoid was increased by both infection of rhizobium and exposure to the normal and pseudo-micro gravity. Chemical species of these flavonoids were identified by LC- ESI/MS and spectroscopic analysis. To show the effects of pseudo-microgravity on the gene expression, enzymic activities related to the functional compounds are evaluated after the rhizobial infection.

Tomita-Yokotani, Kaori; Maki, Asano; Aoki, Toshio; Tamura, Kenji; Wada, Hidenori; Hashimoto, Hirofumi; Yamashita, Masamichi

434

The role of PHB metabolism in the symbiosis of rhizobia with legumes  

Microsoft Academic Search

The carbon storage polymer poly-?-hydroxybutyrate (PHB) is a potential biodegradable alternative to plastics, which plays a key role in the cellular metabolism of many bacterial species. Most species of rhizobia synthesize PHB but not all species accumulate it during symbiosis with legumes; the reason for this remains unclear, although it was recently shown that a metabolic mutant of a nonaccumulating

Maria A. Trainer; Trevor C. Charles

2006-01-01

435

Trophic Interactions Between Two Herbivorous Insects, Galerucella calmariensis and Myzus lythri, Feeding on Purple Loosestrife, Lythrum salicaria, and Two Insect Predators, Harmonia axyridis and Chrysoperla carnea  

PubMed Central

The effects of two herbivorous insects, Galerucella calmariensis Duftschmid and Myzus lythri L. (Coleoptera: Chrysomelidae), feeding on purple loosestrife, Lythrum salicaria L. (Myrtiflorae: Lythraceae), were measured in the presence of two insect predators, Harmonia axyridis Pallas (Coleoptera: Coccinellidae) and Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae). A greenhouse cage experiment examined the direct effects of these predators on these herbivores, and indirect effects of predation on aboveground biomass, defoliation, number of leaves, and internode length. Eight treatment combinations with G. calmariensis, M. lythri, H. axyridis and C. carnea were applied to caged L. salicaria. The experiment ended when G. calmariensis adults were observed, 11 to 13 days after release of first instar G. calmariensis. G. calmariensis larvae alone removed significant amounts of leaf tissue and reduced the number of L. salicaria leaves. Predators did not reduce levels of defoliation by G. calmariensis. C. carnea had no effect on G. calmariensis survival, but H. axyridis reduced G. calmariensis survival in the presence of M. lythri. Both predators reduced the survival of M. lythri. This short duration greenhouse study did not demonstrate that predator-prey interactions altered herbivore effects on L. salicaria.

Matos, Bethzayda; Obrycki, John J.

2007-01-01

436

Trophic interactions between two herbivorous insects, Galerucella calmariensis and Myzus lythri, feeding on purple loosestrife, Lythrum salicaria, and two insect predators, Harmonia axyridis and Chrysoperla carnea.  

PubMed

The effects of two herbivorous insects, Galerucella calmariensis Duftschmid and Myzus lythri L. (Coleoptera: Chrysomelidae), feeding on purple loosestrife, Lythrum salicaria L. (Myrtiflorae: Lythraceae), were measured in the presence of two insect predators, Harmonia axyridis Pallas (Coleoptera: Coccinellidae) and Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae). A greenhouse cage experiment examined the direct effects of these predators on these herbivores, and indirect effects of predation on aboveground biomass, defoliation, number of leaves, and internode length. Eight treatment combinations with G. calmariensis, M. lythri, H. axyridis and C. carnea were applied to caged L. salicaria. The experiment ended when G. calmariensis adults were observed, 11 to 13 days after release of first instar G. calmariensis. G. calmariensis larvae alone removed significant amounts of leaf tissue and reduced the number of L. salicaria leaves. Predators did not reduce levels of defoliation by G. calmariensis. C. carnea had no effect on G. calmariensis survival, but H. axyridis reduced G. calmariensis survival in the presence of M. lythri. Both predators reduced the survival of M. lythri. This short duration greenhouse study did not demonstrate that predator-prey interactions altered herbivore effects on L. salicaria. PMID:20302526

Matos, Bethzayda; Obrycki, John J

2007-01-01

437

Predator cue and prey density interactively influence indirect effects on basal resources in intertidal oyster reefs.  

PubMed

Predators can influence prey abundance and traits by direct consumption, as well as by non-consumptive effects of visual, olfactory, or tactile cues. The strength of these non-consumptive effects (NCEs) can be influenced by a variety of factors, including predator foraging mode, temporal variation in predator cues, and the density of competing prey. Testing the relative importance of these factors for determining NCEs is critical to our understanding of predator-prey interactions in a variety of settings. We addressed this knowledge gap by conducting two mesocosm experiments in a tri-trophic intertidal oyster reef food web. More specifically, we tested how a predatory fish (hardhead catfish, Ariopsis felis) directly influenced their prey (mud crabs, Panopeus spp.) and indirectly affected basal resources (juvenile oysters, Crassostrea virginica), as well as whether these direct and indirect effects changed across a density gradient of competing prey. Per capita crab foraging rates were inversely influenced by crab density, but they were not affected by water-borne predator cues. As a result, direct consumptive effects on prey foraging rates were stronger than non-consumptive effects. In contrast, predator cue and crab density interactively influenced indirect predator effects on oyster mortality in two experiments, with trait-mediated and density-mediated effects of similar magnitude operating to enhance oyster abundance. Consistent differences between a variable predator cue environment and other predator cue treatments (no cue and constant cue) suggests that an understanding of the natural risk environment experienced by prey is critical to testing and interpreting trait-mediated indirect interactions. Further, the prey response to the risk environment may be highly dependent on prey density, particularly in prey populations with strong intra-specific interactions. PMID:22970316

Hughes, A Randall; Rooker, Kelly; Murdock, Meagan; Kimbro, David L

2012-09-07

438

Predator Cue and Prey Density Interactively Influence Indirect Effects on Basal Resources in Intertidal Oyster Reefs  

PubMed Central

Predators can influence prey abundance and traits by direct consumption, as well as by non-consumptive effects of visual, olfactory, or tactile cues. The strength of these non-consumptive effects (NCEs) can be influenced by a variety of factors, including predator foraging mode, temporal variation in predator cues, and the density of competing prey. Testing the relative importance of these factors for determining NCEs is critical to our understanding of predator-prey interactions in a variety of settings. We addressed this knowledge gap by conducting two mesocosm experiments in a tri-trophic intertidal oyster reef food web. More specifically, we tested how a predatory fish (hardhead catfish, Ariopsis felis) directly influenced their prey (mud crabs, Panopeus spp.) and indirectly affected basal resources (juvenile oysters, Crassostrea virginica), as well as whether these direct and indirect effects changed across a density gradient of competing prey. Per capita crab foraging rates were inversely influenced by crab density, but they were not affected by water-borne predator cues. As a result, direct consumptive effects on prey foraging rates were stronger than non-consumptive effects. In contrast, predator cue and crab density interactively influenced indirect predator effects on oyster mortality in two experiments, with trait-mediated and density-mediated effects of similar magnitude operating to enhance oyster abundance. Consistent differences between a variable predator cue environment and other predator cue treatments (no cue and constant cue) suggests that an understanding of the natural risk environment experienced by prey is critical to testing and interpreting trait-mediated indirect interactions. Further, the prey response to the risk environment may be highly dependent on prey density, particularly in prey populations with strong intra-specific interactions.

Hughes, A. Randall; Rooker, Kelly; Murdock, Meagan; Kimbro, David L.

2012-01-01

439

Size-density scaling in protists and the links between consumer-resource interaction parameters.  

PubMed

Recent work indicates that the interaction between body-size-dependent demographic processes can generate macroecological patterns such as the scaling of population density with body size. In this study, we evaluate this possibility for grazing protists and also test whether demographic parameters in these models are correlated after controlling for body size. We compiled data on the body-size dependence of consumer-resource interactions and population density for heterotrophic protists grazing algae in laboratory studies. We then used nested dynamic models to predict both the height and slope of the scaling relationship between population density and body size for these protists. We also controlled for consumer size and assessed links between model parameters. Finally, we used the models and the parameter estimates to assess the individual- and population-level dependence of resource use on body-size and prey-size selection. The predicted size-density scaling for all models matched closely to the observed scaling, and the simplest model was sufficient to predict the pattern. Variation around the mean size-density scaling relationship may be generated by variation in prey productivity and area of capture, but residuals are relatively insensitive to variation in prey size selection. After controlling for body size, many consumer-resource interaction parameters were correlated, and a positive correlation between residual prey size selection and conversion efficiency neutralizes the apparent fitness advantage of taking large prey. Our results indicate that widespread community-level patterns can be explained with simple population models that apply consistently across a range of sizes. They also indicate that the parameter space governing the dynamics and the steady states in these systems is structured such that some parts of the parameter space are unlikely to represent real systems. Finally, predator-prey size ratios represent a kind of conundrum, because they are widely observed but apparently have little influence on population size and fitness, at least at this level of organization. PMID:22803630

Delong, John P; Vasseur, David A; Meiri, Shai

2012-07-16

440

Spatial decomposition of predation risk using resource selection functions: an example in a wolf-elk predator-prey system  

Microsoft Academic Search

Predation is a fundamental ecological and evolutionary process that varies in space, and the avoidance of predation risk is of central importance in foraging theory. While there has been a recent growth of approaches to spatially model predation risk, these approaches lack an adequate mechanistic framework that can be applied to real landscapes. In this paper we show how predation

M. Hebblewhite; E. H. Merrill; T. L. McDonald

2005-01-01

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